Specify to Ultisnips where are snippets.
For some reason he can edit it but don't use it. If you want to use an different directory than the default you have to :
     * create a directory into one directory of the runtimepath list. (That's why I have add the ~/.vim directory)
     * specify that directory name into the variable g:UltinipsSnippetDiretories
     * for making yours snippets editable add the full path this time into g:UltiSnipsSnippetsDir
     * Enjoy. :D