Merge remote-tracking branch 'origin/master' into v0.2

* origin/master:
  Update HISTORY.md
Merge branch 'master' into v0.2
Merge branch 'master' into v0.2
Add stable installation instructions
Merge branch ‘master’ into v0.2 and update DOKKU_VERSION
Use $DOKKU_ROOT instead of $HOME
Bump to RC3
Add a list of known issues.
Fix commands, the easy way.

Don't use pluginhook to run the commands hook, just run all the scripts
in a loop.
Don't explicitly specify streams to docker run.

Now that "docker run" always has an stdin, we don't need to explicitly
specify stdout and stderr.
Remove known issues and add note about ForceTTY

These issues are fixed by this PR.
Close stdin before running the backup-export hooks.

This avoids hanging when we're not in a pty.
Bump to RC4
Add an empty help message to the nginx-vhosts plugin.

Not doing anything just destroys the help message coming from previous
plugins. Run cat to forward stdin into stdout.
Bump to RC5
Bump to v0.2.0
Update PREBUILT_STACK_URL
Update Makefile from master
Add plugins