Fix ack binary check and update docstring
Merge pull request #513 from tuhdo/helm-projectile-ack

Fix ack binary check and update docstring
Autoload projectile-kill-buffers
Merge pull request #517 from purcell/patch-1

Autoload projectile-kill-buffers
Make projectile-replace's param optional
Fix helm-projectile-find-dir

The command is fixed to populate a list of directory at init time, not
when we want to get a list of candidates. Otherwise, the command usually
presents an empty list.
Merge pull request #518 from tuhdo/master

Fix helm-projectile-find-dir
Merge known-project lists from multiple processes