Updated the documentation to better match the way things work now that 172cd28 is merged.
add enable_debug method to MRuby::Build and build debug version in travis-ci
fix realloc error
Merge pull request #1593 from perlun/patch-1

Updated the documentation to better match the way things work now that 172cd28 is merged.
Merge pull request #1595 from take-cheeze/filename_realloc_fix

get_filename_table_size realloc fix.