Add sample_aspect_ratio attribute from AVCodecContext
Merge pull request #9 from jerdfelt/sample-aspect-ratio

Add sample_aspect_ratio attribute from AVCodecContext
Fix link to docs
Replace autoconf with ctypes

HAVE_funcname for functions and USE_libname for
libraries.
Test libav on Travis

Really untested.
apt-get update
Manually look for libs on Linux

Also, replace check_output for 2.6.
fix libav build
Demonstrate that circular references aren't collected.
Stream and Codec hold onto ContextProxy

This never forms circular references.
Starting the great reorganization

Imports were not fixed, or fixed really badly.
The great reorg takes another turn
Fix a lot of imports

Only tested with examples/decode.py
Use err_check
LibError extends RuntimeError; shuffle imports
AVError extends EnvironmentError; start testing

This is much more like IOError or OSError.
Setup Travis to run actual tests
Fix the docs
The package name is "nose", not "nosetests"
Testing with Vagrant