Enumeration Correction in C-Interface

Following issue #144.
@alikh31 this test is OK and leave it here. Please correct the blueprint snippet of the test above (it wasn't copied properly). 

Also note I have tried to summarize a SOP of fixing a bug in Snow Crash – https://github.com/apiaryio/snowcrash/wiki/HOWTO:-Fixing-a-bug-in-Snow-Crash