This adds support for filtering list results. Filter strings are
passed from Helm to Tiller, where they are compiled as regular
expressions and executed against the list of releases. Only matching
releases are returned.
Filters are applied before limits and sorts.
This adds support for dry run on install, as well as providing
enough info for an install to display (verbose) manifests. While
doing this, I ended up just storing the rendered manifests for
simplicity.