MAINT: Removes unused currentValue method on Position object.

This method became unused when vectorizing position totals.
MAINT: Restricts dates to trading calendar in risk comparison test.

Converts the risk iterative and batch comparison tests to use
the trading environments next date, instead of just advancing by day,
so that the returns being passed into the RiskMetrics in the unit
test are using the same trading calendar as the internal checks for
trading days.

Fixes a case where empty return periods were being into
`calculate_period_returns`

Clearing the way for the pandas based optimization of the risk module.
BUG: Avoids install errors caused by lack of pandoc binary.

The pyandoc module throws an OSError of:
"No such file or directory",
when the underlying pandoc binary does not exist.

This error has caused confusion for numerous people during pip
installation.

pandoc is only needed on upload to PyPI to convert to ReST.
So, instead of doing a try/except on the `import pandoc` for all cases,
now checking whether or not 'upload' was invoked when calling setup.py,
so that only maintainers have to worry about installation of pandoc.

By only exercising the pandoc logic when
REL: v0.5.8

- Fixes bug/confusion caused by pandoc conversion in setup.py
- Slight refactorings, removing missing methods, etc.
MAINT: Adds floating point tolerance to risk metric comparison tests.

In preparation of changing how risk metrics are calculated,
this makes the checking of results more tolerant to floating point
rounding, since upcoming changes change the results by a neglible margin.
ENH: use array and pandas operations to speed up risk computations
ENH: Wires minutely emission of data from performance tracker.

Wires up performance tracker so that when `emission_rate` is set
to `minute`, the performance packets are sent out every minute,
instead of once per day.

Please note, the performance packets that are generated are not
ready for prime time consumption, this patch is merely a step towards
hooking up the ability to inspect minute data.

Known issues:
- The packets do not currently include risk information.
  Since we need to consider how this affects the denominators
  of the risk calculations.
MAINT: Updates copyright year on finance module.
MAINT: Moves exchange to utc conversion inside of environment object.

So that the environments' exchange time is used without having to
specify it independently.

Also, moves uses of Delorean.shift for the exchange conversion inside
of environment to use the exchange_dt_to_utc method.
DEV: Handles empty stash case in pre-commit hook.

Handles the case when reword is called and the `commit --amend` invokes
the pre-commit hook, when there is no stash the `git stash pop -q`
in that case leaves the rebase in an odd state.
Fixes by only calling the stash pop if changes were saved.
MAINT: Use numpy for risk period returns.

Following the lead of the RiskMetricsBatch conversion to use
more pandas and numpy.
Bringing the iterative and batch versions closer together as we
work towards folding them into one.
DEV: Fixes typo in git stash message comparison.
MAINT: Factor out risk metric logic from risk objects.

Move the risk metric definitions to functions at the module level
with defined parameters.

Both risk implementations call these functions, where the difference
between risk implementations is with which internal data they
send to the various risk metrics.

Metrics moved:
- Sharpe Ratio
- Sortino Ratio
- Information Ration
- Alpha
MAINT: Use trading day increment instead of timedelta in test factory.

In the test factory creation of returns, the date creation was using
a timedelta of one day instead of incrementing by trading days.

Working towards changing risk module behavior which would leverage
the trading day map, but tests fail because non-trading days are
created.

Remove `factory.create_returns`, moving uses of that function to us
`factory.create_returns_from_period`, since the number of days input
for `create_returns` was more difficult to use when specifying ranges
over arbirtray dates.
BUG: Fix error during benchmark update over empty period.

On ranges with missing data from Yahoo, e.g.:
On 2013-04-2 the date range of April 2013-03-29 failed because
of the first day in the range being Good Friday, and the API not
yet updating for the Monday after.

Handle the 404 that is found by raising and warning that no
benchmark data was found, but continuing on.
REL: v0.5.9

Highlights:

- Benchmark updating now permits empty ranges.
  (Fixes runtime crash when running immediately after Easter 2013.)
- Risk metrics
  - Performance improvents from converting to numpy and pandas.
    <@wesm, wesmckinn@gmail.com>
  - Refactoring of risk metric calculation out of class structure.
MAINT: Rename risk metric function names to include '_ratio' suffix.

To make the risk metrics being calculated more clear, change the
naming convention that ratios have a '_risk' suffix.

Also, fixes typo in beta docstring.
DEV: Update pegged version of requests. 1.1.0 -> 1.2.0
MAINT: Remove unused RiskReport.find_metric_by_end
MAINT: Use dateutil module for adding months to a datetime.

Instead of having an advance_by_months function maintained in
Zipline, leverage the relativedelta module provided by dateutil.