Disable helm-quick-update

It is not needed anymore since helm-candidate-number-limit is
small (less than several thousands). If this is the case, then there's
no difference between quick update and no quick update execution time.
Enabling helm-quick-update makes helm buffer flashing for every entered
character to retrieve new candidate list, which would annoy user.
Merge pull request #741 from tuhdo/master

Disable helm-quick-update
Add prelude-term-buffer-name variable

This provides multi-term support via .dir-locals.el for example.
Merge pull request #737 from dougm/term-buffer-name

Add prelude-term-buffer-name variable
Merge upstream/master