responses to code review & minor fix

- change architectures to OSArchitectures (since we now have
different client architectures as well)

- change PackageQuery and ReleaseQuery to take in options of everything,
instead of taking the record separately.

- change comment clarifications of 'mandatory' vs. 'optional' to be more
clear.

- remove leftover comment and check for ENOENT, since tropohouse.installed
no longer throws that error.

- fix spelling in comments

- (also, unrelated to code review) fixed a minor bug involving local packages
and added a test for it.