Add physical length parsing to FakeReader
Fix hot-bio-formats OMERO target
Return true unit rather than base

Each quantity was returning some base unit from
its `unit()` method. This led to all imports being
of length "meter" for example, rather than in., ft.,
mm., etc.
Merge pull request #33 from joshmoore/fake-units

Fake units 

This might also fix the issue where Power was always in watts instead of mili watts.