Merge pull request #2 from stoewer/master

Project structure and inheritance from Entity

Great!
Create README.md
Update README.md with link to nix
[travis] Add initial support
[travis] try to convince travis to install libnix from ppa
[travis] need newer boost; manually install libnix
[travis] really install newer libboost. I mean it!

*sigh*
[travis] Use a different ppa for boost; also new libstdc++
[travis] Only install the boost packages we need
[travis] libnix needs boost regex 1.53.

Close to giving up. /-;
[travis] fix ppa install line
[travis] try a different ppa for boost 1.53
[travis] Also install libboost1.53-dev
[travis] remove conflicting boost versions
Merge pull request #3 from stoewer/master

Bindings for EntityWithSources and EntityWithMetadata

Sweet!
accessors.hpp: move to src
transmorgify.hpp: move to src
entity.hpp: move to src and rename
setup.py: change include path to src
"PyEntity: adopt naming schema"