New custom dimension and metric handling.
Merge branch 'master' into dev
Merge branch 'master' into dev
Merge branch 'dev' of https://github.com/AttackPattern/CSharpAnalytics into dev
Merge branch 'master' into dev
Merge branch 'master' into dev
Rework thread-safety of custom metrics and dimensions for WinPhone compat.
Push CheckInternetAvailable down to BackgroundHttpRequester base class.
Split background and network sending code to simplify for WinPhone.
Merge branch 'dev' into winphone-8

Conflicts:
	Source/CSharpAnalytics/Network/BackgroundUriRequester.cs
	Source/CSharpAnalytics/Protocols/Measurement/MeasurementAnalyticsClient.cs