plugins subsystem & mercurial integration

Now vundle can process records like this: 
Bundle 'hg+https://softvisio@bitbucket.org/softvisio/vim-softvisio-sessionman'
Substring before first "+" occurrence is a plugin name. If plugin name detected - functions from particular file vundle#plugin#<PLUGIN_NAME> will be used instead of git - related functions.

Sorry for my english.