Rename classes to Teller prefix

[levibostian]

At this time, we have the Teller repository named Repository, for example. Repository is a common term in mobile development right now. There are chances you have other Repository classes in your code.

Some other libraries follow a pattern of prefixing the names with the name of the library. Example: Moya uses MoyaProvider.

I propose that we prefix the public classes in the repo to a Teller prefix. Possibly rename internal classes to as the library has evolved a bit over the past year and the roles of classes may have changed.