make py.test find test files

pytest is able to run the nose tests, but it needs a bit of help to
find them. since it reads the tox.ini file, we just need to add a glob
pattern there.

py.test will also create __pycache__ directories. add them to
.gitignore.
Handle IndexAlreadyExistsException when nested in RemoteTransportException.

This happens if one node of a cluster raises the exception instead of
the one the client is connected to. The exception string looks like this
for example:

  RemoteTransportException[[hostname][inet[/someip:1234]][indices/create]]; nested: IndexAlreadyExistsException[[main_index] Already exists];
Cleanup _percolate index so it isn't left behind from tests.
Merge pull request #125 from robhudson/percolate-cleanup

Cleanup _percolate index so it isn't left behind from tests.
Merge pull request #102 from brainbot-com/pytest-support

make py.test find test files
Missed quote in example
Merge pull request #130 from rboulton/patch-1

Missed quote in example