FreeBSD installation, add system LD_LIBRARY_PATH

FreeBSD 10/11-CURRENT may not install without adding it.
Merge pull request #1271 from tony/patch-2

FreeBSD installation, add system LD_LIBRARY_PATH
Updating to latest ycmd
Ignoring the new "already being parsed" message

This exception comes from ycmd and is not something the user can do
anything about, so let's rather not show it.
Updating vimdoc from README