Add datetime helper that sets utc timezone info, and fix utils docs while I'm here
refactor util to its own module, and add timezone helpers as its own file rather than a fake-datetime module
Update docs
add better docs, fix minor issue
Correct python comment syntax for docs
Add copyright header and tests
This had passed in local testing on cruncher --- somehow. Also fix a .rst issue
pep8
Merge Callek/build-relengapi:datetime_helper (PR #55)