Speed up testable msfcli

msfcli is used by users who already know what module(s) they want to use, so we shouldn't have to load all of them to run this utility. The overall goal of this PR is to narrow down what modules (exploit/aux + payload + encoder + nop + post) you possibly need in order to shave off loading time. By doing this, on my box this is 5-6 seconds faster than the original one.

To test msfcli, here's how:

	$ rspec spec/msfcli_spec.rb