Updated factory methods, removing stored test context from factory and removing varargs for creation methods.
Merge pull request #490 from tasdomas/factory-followup-fixes

Remove varargs and test context object from factory.

Due to lifetime differences, it is impractical and not recommended to set the test context for the factory during initialization, so all creation methods (MakeUser, MakeService, etc.) now take an additional *gc.C parameter.

Also, variadic parameters are exchanged for a pointer parameter for object properties - MakeUser() becomes MakeUser(c, nil). This makes the code more readable and idiomatic.
Added support for a metrics collections

insert a batch of metrics instead of one at a time

only allow metrics to be added if the unit is alive
use right version of charm as per master
Merge pull request #466 from mattyw/add-metric-collection-to-state

Added support for a metrics collections

Added a metric collection for storing unit metric in the state server

Only support for:

* adding new metrics
* getting lists of unsent metrics
* setting the sent flag