Fix check credentials, logging messages.

Protip: Don't use \n with echom
Exit follow mode on insert mode.

Also stop doing fileio on every nvim autocmd when not connected to the
workspace. Explicitly check we're connected to workspace for every
autocmd.

Closes issue #18
Fix maybe new buffer inverted logic.

Remove debug comments.
Strip new lines from any UI messages to vim as they look broken.
Remove sync version of this command, no reason for it.
pep8 and pyflakes fixes.
Update part of buffer when possible.

Also fixed problem where we weren't printing stack traces to log when
not sending an error email.
In practice this updates usually only one line. Even with big files
iterating and comparing each line should not be noticeable.
Give up and stomp entire buffer on new line. Any change made to the vim
python buffer array will add to the undo history.

This also fixes a problem with sending patches for changes received from
workspace.
Merge commit '97b6bc8057476cb08950473eaf7238fb28e1739d'