Fixes to work with MASC 3.0.x and other clean up

Hi,

A few changes listed below:

1. Tuples are immutable but media.py's `Region` class has `anchors` attribute that tries to adjust it's start and end values in-place. Changed to be a list. Also changed `get_region` function in graphs.py as it will compare against the `anchors` attribute of an instance of `Region`.

2. Remove "retu" typo from `get_location` function in io.py.

3. Standardized use of property decorators rather than using both decorators and function calls in class body.

4. Ignore first two characters from f.id value if starting with "f." as this **is not** part of the filename and will produce errors like,

> IOError: [Errno 2] No such file or directory: u'.../data/spoken/court-transcript/Day3PMSession-f.seg.xml'

Where the file it should be looking for is actually "Day3PMSession-seg.xml".

Thanks,
Jared