[SNEAKER-58] Implement support for recursive definition in JSON schema
[SNEAKER-60] JSON schema semantic format validation
[SNEAKER-62] Update top level docstring in include/json/json_schema.h
[SNEAKER-63] Fix test compilation failure on OS X
[SNEAKER-64] JSON schema validation tests cause seg fault on OS X
[SNEAKER-65] Update Makefiles to use the right compilers
[SNEAKER-66] Update .travis.yml to fully build libsneaker.a
Version 0.2.7