Image plugin: old revisions thumbnail error

Simple typo error.
Merge pull request #232 from vincentalvo/patch-1

Image plugin: old revisions thumbnail error
Fixed incorrect indentation
Executable scripts 'setup.py' and 'runtests.py'
Added method to allow selected tests to be run, instead of running all.

This also removes the use of the deprecated DjangoTestSuiteRunner class
Fix for issue #225 (exception when running with ATOMIC_REQUESTS), and the same applied to deleting subtrees

All explicit transaction handling has been moved to the model layer, and
uses transaction.commit_on_success or transaction.atomic, depending on the
Django version.
Added tox.ini and instructions, for easy running of tests in multiple environments
Merged wiki.compat into wiki.core.compat
Replace PIL with Pillow

Somehow PIL is not making Travis very happy atm.
Merge pull request #241 from spookylukey/fix_transaction_management

Fix transaction management - issue #225
Update installation.rst
Update installation.rst
Merge pull request #248 from andyreagan/patch-1

Update installation.rst
Merge pull request #249 from andyreagan/patch-2

Update installation.rst
Fixing requirements list
Update installation.rst
Merge pull request #250 from valberg/master

Fixing documentation