RBTools currently must scan the filesystem when a user does not specify a

repository name or repository type which is very slow. In order to optimize

RBTools, we will log hints that recommends setting repository name or type

when it has not been specified. An option --no-hints is added so

users can disable hints if desired.

I ran ./tests/runtests.py rbtools/ and have 263 tests passing and have done 

manual testing on different rbtools commands to ensure that the --no-hints 

option is working and is also presented as an option to the user when they 

type rbt [command] --help.