Signal-analog

* The `percentile` function on `signal_analog.flow.Data` objects has been
fixed to use the correct constructor

* signal-analog now prefers `simplejson` if it is available on the path,
falling back to the `json` module otherwise.

* DashboardGroup has learned how to accept SignalFX Team ids so that they can
be associated with pre-existing teams via the `with_teams` builder method.

Fixed
* Add `deprecation` to setup.py.

Changed
* Added `with_secondary_visualization` function to enable display of various meters (Sparkline, Linear, Radial) in
Single Value charts. This replaces the now defunct `with_sparkline_hidden` function. This will not be a
'breaking change' until version 3.0.0 when `with_sparkline_hidden` will be removed from `signal_analog`.

* Added the `deprecation` Python library to this project to note when `with_sparkline_hidden` should be removed. Upon
version matching 3.0.0 or higher the tests for that function will begin to fail notifying whoever is releasing that
version to remove the defunct `with_sparkline_hidden` function and tests.

Changed
* Dashboard Create method to accept group id of an existing dashboard group in which case the new dashboard will be
part of the dashboard group provided

Example:
python
response = dashboard\
.with_charts(memory_chart)\
.with_api_token('my-api-token')\
.create(group_id="asdf;lkj")

* Dashboard Group create method to pass group id of the newly created dashboard group to the dashboard create
method so that we can avoid a few redundant calls like cloning and deleting the dashboards