Use NSDate instead of GCD time in RACScheduler
Add RACQueueScheduler method for calculating walltime
Refactor schedulers and unit tests to use NSDate
Implement +switch:cases:
Implement +if:then:else: using +switch:cases:
Fixed grammr
Revert "Implement +if:then:else: using +switch:cases:"

This reverts commit 3a0fa78f5089aaf3001a38c23cfb194ce76864a9.
Improving +switch:cases:
Fixing documentation of +switch:cases:
Implement +switch:cases:default:
Extracting common specs into RACSwitchSignalExamples
Test +switch:cases:default: for nil values
Extract common logic into +switch:cases:useDefault:default:
Merge branch '2.0-development' into switch-case

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa.xcodeproj/project.pbxproj
Merge pull request #658 from robb/switch-case

Add +switch:cases:
totes unused
Merge branch '2.0-development' into date-based-scheduling
Fix argument indentation
Fix method name in RACImmediateScheduler
Merge pull request #664 from ReactiveCocoa/date-based-scheduling

Use NSDates for scheduling, instead of dispatch_time_t