Merge pull request #2212 from mwcraig/patch-4

Change test coverage dependency
Ensure name-less columns can be printed, plus test case and bug-fix note.
Don't generate .pyc files when running tests
str -> six.text_type, move change to 0.3.2 bug-fix section
Merge pull request #2214 from mdboom/misc/dont-write-pyc

Don't generate .pyc files when running tests
Merge pull request #2213 from mhvk/column-no-name-header

Column with no name cannot be printed
Update development_workflow.rst

typo fix
Merge pull request #2220 from larrybradley/patch-1

Update development_workflow.rst
Restructure front documentation page to emphasize contributions rather than development
Example of reworked documentation aimed at beginners
Clarify language in several places
Change line breaks to keep length under 80 characters
Fix typographical errors
Add caveats about cases when setup.py develop will fail
Clarify warning about need to reactive development astropy

New wording suggested by @mdboom
Fix line that was too long
Add summary of virtual environment commands for anaconda and virtualenvwrapper
Condense git installation/configuration instructions
Fix typographic errors
Minor wording changes and link updates