Scenedetect

This release improves the performance of content detection mode, adds a new command line option for selecting fade bias (threshold mode only), and includes various other improvements. List of changes included:
- [enhance] added scene length, in seconds, to output file (`-o`) for easier integration with `ffmpeg`/`libav`
- [enhance] improved performance of content detection mode by caching intermediate HSV frames in memory (approx. 2x faster)
- [enhance] show timecode values in terminal when using extended output (`-l`)
- [feature] add fade bias option (`-fb` / `--fade-bias`) to command line (threshold mode only)

This release marks the first stable release, includes several bugfixes, and is now [available on PyPI](https://pypi.python.org/pypi/PySceneDetect/). Changes:
- [bugfix] scenes are now written correctly to specified output file when using `-o` flag (fixes 11)
- [bugfix] fix indexing exception when using multiple scene detectors and outputting statistics
- [internal] distribute package on PyPI, version move from beta to stable
- [internal] add function to convert frame number to formatted timecode
- [internal] move file and statistic output to Python `csv` module

This release adds image preview generation and duration (start/stop time) setting via four new command-line arguments ([click here to view some examples](http://pyscenedetect.readthedocs.org/en/v0.3.2-beta/examples/usage/#seeking-duration-and-setting-startstop-times)):
- [feature] added `-si` / `--save-images` flag to enable saving the first and last frames of each detected scene as an image, saved in the current working directory with the original video filename as the output prefix
- [feature] added command line options for setting start and end times for processing (`-st` and `-et`)
- [feature] added command line option to specify maximum duration to process (`-dt`, overrides `-et`)

New release with two new command line options - down sampling and frame skipping - both focused on performance/efficiency.
- [feature] added downscaling/subsampling option (`-df` / `--downscale_factor`) to improve performance on higher resolution videos
- [feature] added frameskip option (`-fs` / `--frame_skip`) to improve performance on high framerate videos, at expense of frame accuracy and possible inaccurate scene cut prediction
- [enhance] added setup.py to allow for one-line installation (just run `python setup.py install` after downloading and extracting PySceneDetect)
- [internal] additional API functions to remove requirement on passing OpenCV video objects, and allow just a file path instead

The first major release of PySceneDetect, including all major features and functions. See the new `USAGE.md` file for helpful tips on how to use the new detection modes, and for optimal threshold values to try.

Changes from `CHANGELOG.md` include:
- major release, includes improved detection algorithms and complete internal code refactor
- [feature] content-aware scene detection using HSV-colourspace based algorithm (use -d content)
- [enhance] added CLI flags to allow user changes to more algorithm properties
- [internal] re-implemented threshold-based scene detection algorithm under new interface
- [internal] major code refactor including standard detection algorithm interface and API

Bugfix with OpenCV version checking code - from the previous release, v0.2.3-alpha - for older versions of OpenCV (2.4 and older) on certain Linux distributions.