Fix for issue 16 (Keep track of injuries)

Added function scrape_injury_report to InjuryManager and set it to run
in determine_injuries.py when provided with the type=current flag.
Also added associated test cases and
Changed print statements to logging.info().
Added function to print out depth charts.

Depth charts are now generated for each site.  This is helpful for
figuring out who might make good value plays.  The depth charts contain
average minutes, expected minutes, avg FPs, and FP standard deviation.
In order to facilitate having avg FPs, I modified
calculate_scoring_stddev() to return a tuple instead of the stddev.
The tuple contains the avg FPs as the first element and stddev as the
second.

Also removed depth_chart and depth_chart_by_player_id as instance
attributes.  Now they’re just local variables.
Changed print statements to logging statements.

This makes sure a bunch of shit isn’t printed out in the unit tests.
Modified the depth chart to only look at past two weeks.
Added logging configuration to specify INFO level.
Fix for issue 14 (Make all FP calculations a single command)

Didn’t actually make it a single command, but added the option to
specify a season, which will make the queries run significantly faster.
Modified calculate_defense_vs_position_ranking() signature to include site

We no longer expect site to be a Projections instance attribute.  That
was kind of awkward and easy to forget.  This makes more sense.

This solves the problem of the depth chart printouts having the same
DvP for each team, regardless of position.