We used to specify specific rake test tasks so that we could run all of
them even if early ones failed. However, that meant that as new tasks
were added, they weren't being run on jenkins.

Now, there is a facility in the rake scripts so that tests can run using
the test_sh function, which will delay failure until the end of the rake
run, unless the TESTS_FAIL_FAST environment variable is set.

Furthermore, this reorganizes the jasmine test tasks so that we can run
those as part of `rake test` as well.

Added diff coverage reports using diff-coverage tool.

installed.

in parallel.

Updated docs to say we target Chrome.

moved syncdb/migration steps into the rake test_acceptance commands
and updated the documentation.

Updated testing docs to reflect changes to the rake file

Added option to pass arguments (including --pdb) to rake test_acceptance
Updated readme

Updated jasmine rake documentation to reflect changes Cale made

Fixed mistake in pip install snippet