Remove plugins before copying them again.

This way plugins can rename/delete files w/o having old files lying around.
Only delete core plugins.
Added man page plugin command warning

As of now, the man page does not update when plugins are installed.
Updated man page date

I forgot to change it. I even left myself a reminder!
Use PLUGIN_PATH in dokku default case.
move post-deploy hook

Write $DOKKU_ROOT/$APP/URL before post-deploy hook.
port 'wait_to_retire' from broadly/dokku
Revert "Add CNAME option"
Merge pull request #696 from progrium/revert-657-CNAME_option

Revert "Add CNAME option"
Make help output more consistent
Actually suppress the output from the git commands
Fixed key format check
Display help when invoking dokku with no parameter
Merge pull request #701 from jazzzz/fix-key-format

Fixed key format check
Merge pull request #703 from jazzzz/help-with-no-parameter

Display help when invoking dokku with no parameter
Consolidate readme/wiki docs into organized docs folder
Merge pull request #706 from progrium/docs

Consolidate documentation for viewthedocs
Use -qq flag on apt-get to quiet installations of packages
Silence curl stderr progress output
Ensure curl is installed before using command