New CLIColor class:  Simple NSColor replacement for CLI projects that don't link with AppKit
Make 'Extensions' the `default_subspec`
Add 'CLI' subspec for OS X projects that don't link with AppKit
DDTTYLogger: Use CLIColor objects when COCOAPODS_POD_AVAILABLE_CocoaLumberjack_CLI is defined in Pods-environment.h
Ignore Pods directories
Add CLI Demo