Added build directory to gitignore

phpunit creates a clover report in build/logs
Merge pull request #29 from arekkas/patch-2

Closes #28
Merge pull request #30 from arekkas/patch-3

Added build directory to gitignore
Merge pull request #26 from arekkas/idgenfac

IdGeneratorPluginManager is now being instantiated through a factory whi...
Merge remote-tracking branch 'upstream/master' into patch-2