Add 'rate' command
Fix line length
Refactor to helper method on gh
Add callback rv from __call__ for show_rate

Since each `__call__` method calls the supers
call, there's no way to have all implementors
do something on function end. If this is too
invasive probably a global registry of call-
back objects would be best.
merge master -D org: PR 159 (Tag release prefix)
merge master -D org: PR 165 (Add 'rate' command)
merge master -D org

Repository: openmicroscopy/snoopycrimecop
Excluded PRs:
  # PR 167 sbesson 'Reduce max complexity' (status: pending)
Already up-to-date.

Merged PRs:
  # PR 159 sbesson 'Tag release prefix'
  # PR 165 joshmoore 'Add 'rate' command'

Generated by SCC-merge#333 (http://ci.openmicroscopy.org/job/SCC-merge/333/)