Adds YcmLock and YcmUnlock commands to temporarily prevent autocompletio...

Added Vim commands for temorarily locking(disabling) and unlocking(enabling) autocomplete trigger as you type (on cursor move).
To lock it, just use command:
````
:YcmLock
````
And to unlock it:
````
:YcmUnlock
````

YCM generall works fine with https://github.com/kristijanhusak/vim-multiple-cursors, but it slows it a bit. Adding this to vimrc can be small improvement:
````
" Disable autocomplete before multiple cursors to avoid conflict
function! Multiple_cursors_before()
    exe 'YcmLock'
endfunction

" Enable autocomplete after multiple cursors
function! Multiple_cursors_after()
    exe 'YcmUnlock'
endfunction

````