Preparing release 0.4.2
Back to development: 0.5
Make it easier to run tests on installed Pint.
Adds another units library to faq.rst

- Adds udunitspy
Extract out formatting rules into separate dictionaries.
Fix https://github.com/hgrecco/pint/issues/112 and add _DEFAULT_FORMAT
Split off the formatter into its own file.
Move the constant arguments for formatting to formatter.py
Move the constant arguments for formatting to formatter.py
Fully parse the spec, fixing https://github.com/hgrecco/pint/issues/111
Merge branch 'rec-issue-107' of https://github.com/rec/pint into rec-issue-107
Started to write unit tests.
Finish tests for new condensed formatting mode.
Merge branch 'rec-issue-107' of git://github.com/rec/pint into rec-rec-issue-107
Fixed conflicts with rec-issue-107 and merged