Merge branch 'feature-travis-ci' into develop
Merge branch 'hotfix-travis-cxx11' into develop
try to fix notifications
fix the preprocessor condition
remove cxx11 build
add a document on the status of C++11 for this project
add a CONTRIBUTING file
bump version to 0.5.2
update ChangeLog for version 0.5.2
Merge branch 'release-0.5.2'