Readme has insufficient boost version

[paulshapiro]

Hey there,

Readme indicates an older than necessary version of boost given e.g. beast now

[vtnerd]

The README.md in develop has been updated to indicate Boost 1.70 is the targeted minimum. The master branch (as seen by default on Github) still indicates Boost 1.58 as the Beast changes have not been merged into master. The README.md on master will likely get updated when the related code gets merged.

[vtnerd]

I think the gcc version needs to be bumped too, for both master and develop.