Add Nicknames to User Model; Bump README to 0.9.1

Add `User.IsBot` field, bump version number to 0.9.1

A few users requested an IsBot field for marking Bot Accounts;

Bumping Version number because it has been 0.9-rc3 forever and that's caused a bit of confusion in the channel with what version users are on.

Removed hack

check for server==null in User.ServerPermissions getter

Voice crashfix, Properly getting data for large servers.

Preliminary Unit-Testing

- Test User Mentions
- Test User Edit [UserUpdatedEventArgs]
- Test CurrentUser.Edit [UserUpdatedEventArgs]
- Test SetStatus 
- Test SetGame

- Test for Server.GetChannel
- Test for SendTyping [ChannelUserEventArgs]
- Test for EditChannel [ChannelUpdatedEventArgs]
- Test for Channel Mentions
- Test for DownloadMessages with/without cache
- Test for SendTTSMessage

- Test AddGet Permissions
- Test AddRemove Permissions
- Test Permissions triggering ChannelUpdated
- Test HttpException triggered when affecting permissions in an invalid channel.

Environment Vars will be used for storing credentials, to maintain compatibility on the CI.

Test adding Permissions Rules and retrieving Permissions Rules

MessageQueue silently handles all exceptions, cannot test for them.

Test Events for Send/Update/Delete Message
Test Exceptions for:
- Send to a Deleted Channel
- Send to a Channel with No Perms
- Update a Deleted Message

Fixed up existing code for Unit Tests,
Added EventArgs-less AssertEvent,
Added Tests for READY and JoinedServer
Temporarily moved initialization to it's own Test, may leave there?