Commits on Jan 11, 2016

  1. lower cmake requirement to 3.1.0 

    eaf7229 suggests that it was bumped to
3.2 for CMAKE_CXX_STANDARD, this feature was however introduced in 3.1.

lower the cmake requirement from 3.2 to 3.1 to align with the actual
requirements
    @hsitter
    hsitter committed Jan 11, 2016
    8570d06