Improve option parsing

The existing code did not provide for escaping characters, which made
certain option values impossible to represent, for example:

 password='spaces and ' a quote'

In addition, ParseUrl would not allow even a single space in any value.

Add standard backslash escaping, matching libpq's own conninfo_parse.

Apply this escaping to special characters in ParseURL.
Add Lann Martin to list of contributors
Fix time decoding

Compare time.Location names, not just offsets. Unfortuntately, we have
to do this by comparing String representation of time.Times, since
there's no way to compare time.Locations beyond just offset.

Also fix the current parsing tests to expect a zero-offset time.Time,
rather than time.UTC explicitly.