check plugin activities

- refactor rakefile
- add task plugin_activity

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
add plugin activity

- generated by rake plugin_acitivity

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
rmeove doc link and add compat column

Signed-off-by: Hiroshi Miura <miurahr@linux.com>
Merge pull request #2 from vagrant-lists/plugin_check_latest_activity

Plugin check latest activity