Introduce `backup` plugin to export/import settings
Specify current backup version at the top of the script
Introduce DOKKU_ROOT and import now in git plugin
Update buildstep URL and reenable PHP test
Force connection of stdin and stderr in the run command.

If stdin is closed, which is the case when pluginhook is called from an
interactive session, "docker run" does not connect stdin and stderr by default.
Fixes #323
Merge pull request #265 from asm89/backup

Introduce `backup` plugin to export/import settings
Update headers
Provide more feedback for backup import
Update bootstrap.sh

A typo has been corrected.
Merge pull request #325 from ugurthemaster/patch-1

Update bootstrap.sh
Delete the /cache directory's contents from inside the container.

Fixes #322.
Buildpacks write into /cache as root, which made the delete command unable
to delete it.
Its contents are now deleted using "docker run", and thus as root.
Update HISTORY.md
Merge branch 'history'

* history:
  Update HISTORY.md
Add support for DOKKU_TAG in bootstrap.sh

Fixes #330
Refs #329
Use globs, set nullglob, and remove stdout redirection for import
Merge pull request #333 from rhy-jot/2013-11-20/backup-find-to-glob

backup:export: find -> glob
Add a version command.

The git tag/revision is saved when running "make install", and can be
displayed using "dokku version".
Use a hardcoded version if git revision is not available.
Add the date and time of installation if version is hardcoded.
Merge pull request #334 from plietar/version

Add a version command.