Reverted logic that has flake8 run in different venv

Modified the Flake8Task to once again inherit from
AbstractPythonMainSourceDefaultTask and use the original
virtual environment instead of having a dedicated venv just for
it's run. Deleted the AbstractPythonInfrastructureDefaultTask as
Flake8Task was the only class using it.

Modified PythonPlugin to have flake8 be added as a build configuration
instead of it's own configuration. Deleted unit and integration tests
ensuring that flake8 was run in its own environment.

Author: elautz

.circleci/config.yml

@@ -4,7 +4,7 @@ jobs:
         docker:
             - image: openjdk:8-jdk
         environment:
-            _JAVA_OPTIONS: "-Xmx1024m -Xms256m"
+            _JAVA_OPTIONS: "-Xmx768m -Xms256m"
             GRADLE_OPTS: -Dorg.gradle.jvmargs=-Xmx1024m -Dorg.gradle.daemon=false
         steps:
             - run:

pygradle-plugin/src/integTest/groovy/com/linkedin/gradle/python/plugin/ParallelWheelsIntegrationTest.groovy

@@ -92,20 +92,6 @@ class ParallelWheelsIntegrationTest extends Specification {
 
         then:
         out.toString() == "Hello World${ System.getProperty("line.separator") }".toString()
-
-        when:
-        println "======================="
-        result = GradleRunner.create()
-            .withProjectDir(testProjectDir.root)
-
-            .withArguments('flake8', '--stacktrace', '--info')
-            .withPluginClasspath()
-            .withDebug(true)
-            .build()
-        println result.output
-
-        then:
-        result.task(':foo:parallelWheels') == null //the task isn't part of the graph
     }
 
     @IgnoreIf({ OperatingSystem.current() == OperatingSystem.WINDOWS })

pygradle-plugin/src/main/groovy/com/linkedin/gradle/python/plugin/PythonPlugin.java

@@ -42,7 +42,6 @@
 
 import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_BOOTSTRAP_REQS;
 import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_BUILD_REQS;
-import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_FLAKE8;
 import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_PYDOCS;
 import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_PYTHON;
 import static com.linkedin.gradle.python.util.StandardTextValues.CONFIGURATION_SETUP_REQS;
@@ -156,15 +155,11 @@ private static void createConfigurations(Project project) {
 
         project.getConfigurations().create(CONFIGURATION_BOOTSTRAP_REQS.getValue());
         project.getConfigurations().create(CONFIGURATION_SETUP_REQS.getValue());
-        Configuration buildReq = project.getConfigurations().create(CONFIGURATION_BUILD_REQS.getValue());
+        project.getConfigurations().create(CONFIGURATION_BUILD_REQS.getValue());
         project.getConfigurations().create(CONFIGURATION_PYDOCS.getValue());
         project.getConfigurations().create(CONFIGURATION_TEST.getValue());
         project.getConfigurations().create(CONFIGURATION_VENV.getValue());
-        Configuration flake8 = project.getConfigurations().create(CONFIGURATION_FLAKE8.getValue());
         project.getConfigurations().create(CONFIGURATION_WHEEL.getValue());
-
-        //So flake8 will be installed into the activate-able venv
-        buildReq.extendsFrom(flake8);
     }
 
     /*
@@ -183,7 +178,7 @@ private static void configureVendedDependencies(Project project, PythonExtension
         project.getDependencies().add(CONFIGURATION_SETUP_REQS.getValue(), settings.forcedVersions.get("pip"));
         project.getDependencies().add(CONFIGURATION_SETUP_REQS.getValue(), settings.forcedVersions.get("setuptools-git"));
 
-        project.getDependencies().add(CONFIGURATION_FLAKE8.getValue(), settings.forcedVersions.get("flake8"));
+        project.getDependencies().add(CONFIGURATION_BUILD_REQS.getValue(), settings.forcedVersions.get("flake8"));
 
         project.getDependencies().add(CONFIGURATION_BUILD_REQS.getValue(), settings.forcedVersions.get("Sphinx"));