[managed] Added feature header to gauge usage of table types
[managed] Added feature header support for custom API overloads
[managed] Addressed code review feedback for telemetry feature.
[managed] Added telemetry for MobileServiceCollection
[managed] CR feedback
[managed] Features CR feedback:

- FeatureCodeAttribute made into a general-purpose class
- Factor features string code out of HTTP client into helper class
[managed] Cleanup for features (telemtetry) code
Merge branch 'dev' of https://github.com/carlosfigueira/azure-mobile-services into offline

Conflicts:
	sdk/Managed/src/Microsoft.WindowsAzure.MobileServices/Http/MobileServiceHttpClient.cs
	sdk/Managed/src/Microsoft.WindowsAzure.MobileServices/MobileServiceFeatures.cs
	sdk/Managed/src/Microsoft.WindowsAzure.MobileServices/Table/MobileServiceTable.Generic.cs
	sdk/Managed/src/Microsoft.WindowsAzure.MobileServices/Table/MobileServiceTable.cs
	sdk/Managed/src/Microsoft.WindowsAzure.MobileServices/Table/Query/Linq/MobileServiceTableQueryProvider.cs