Allow users to still trigger Vim's omnifunc through C-Space when the
g:ycm_filetype_specific_completion_to_disable option is set for the current
filetype.
Now that the server supports Java natively, we need to use a
filetype that does not have native support to ensure that we call the
mocked omnifunc, but also one for which YCM has a semantic trigger.
Rather than picking another random languagse, which might break in the
future, we invent a language (ycmtest) and supply a manual trigger
mapping to the YouCompleteMe object.
