Implement "last=" keyword in kick/ban, fixes
Implement "last=" keyword in kick/ban, fixes

* Add "last=" keword to kick/ban members that have joined in that amount of time
* Fixed confirmation_user.content issue when the prompt times out
* Use mentions for matched members and name#discriminator for matched users (useful when pre-banning)
* List number of members affected
corpnewt/CorpBot.py,corpnewt/CorpBot.py