Added fix to Issue #29 to Changes
Preparing release 0.2.1
Back to development: 0.3
Adjusted doc examples to Py3
Changed setup.py encoding to make 'python setup.py check -r' work in Python 2.X
Changed docs Makefile to use local sphinx-build when present
Changed formatting codes.

Reasons behind the change:
- uppercase codes are easier to read (in particular 'l' vs 'L', in certain fonts).
- remove the exclamation mark as it does not belong to the format code.
- agreed on formatting with the uncertainties package (See Issue #6).

WARNING: This is a backwards incompatible change affecting string formatting operations.

To update your code, remove any exclamation mark '!' from you
the part after the colon ':' in your format spec.
Additionally, change the letters to uppercase:
- Latex : change 'l' to 'L'
- Pretty: change 'p' to 'P'
- HTML:   change 'h' to 'H'
Merge branch 'master' into develop
Improved UnitRegistry.wraps and created doctests
Changed examples in the formatting documentation to the new specification