Renames filter to base_filter and weight to base_weight

filter is a python builtin function so importing it pollutes ones name
space.

It is now renamed to base_filter.

We also rename weight to base_weight, just to be consistent in the
naming conventions.

We add a test for base_filter.

Fixes bug 1175829

Change-Id: I46e0fa696d2f39081b5568c701b0a70c54f271ab
Line wrapper becomes to long when expanded.

Projects with long names, such as ceilometer, trip up on this line.

Change-Id: I51ff3f0250018215ae240f90cec6051b56aab434
Removes len() on empty sequence evaluation

PEP8 suggestes, "For sequences, use the fact that empty sequences are false."

Change-Id: I4c600a7a6230a55328ee46f7c59f340f37abc18f
python3: use 'as' syntax for exception assignment

From http://docs.python.org/3.1/whatsnew/3.0.html

The except exc as var syntax is now standard and except exc,
var is no longer supported.

Change-Id: Ia3a11d72c474806cc2303a7fc9cb1a390266c0fb
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Merge "python3: use 'as' syntax for exception assignment"
Merge "Renames filter to base_filter and weight to base_weight"
Merge "Line wrapper becomes to long when expanded."
Merge "Removes len() on empty sequence evaluation"
Update eventlet bug URL.

The eventlet repository has moved, so the bug url referenced
in the comment about why we patch eventlet needs to be updated.

Change-Id: I55abe0b6eb4c8e21fad15a10d6ec71d3b5a59e54
Merge "Update eventlet bug URL."