Adding SFSDKAppConfig file
SalesforceSDKManager for hybrid
Fixing offline flow in hybrid
Adding InitialViewController to hybrid sample apps
Updating remaining native samples to SalesforceSDKManager.

Note: FileExplorer (Swift) is still TODO.
Changing snapshot to resign and resume active
Fixing session refresh logic to allow for absolute URLs
Updating copyrights
Merge pull request #750 from khawkins/salesforce_sdk_manager

Salesforce sdk manager