Improve system version detection over #171

When building against iOS 6 SDK `NSFoundationVersionNumber_iOS_6_0` and `NSFoundationVersionNumber_iOS_6_1` may not be defined.

Replaces #186.
Merge pull request #187 from rivera-ernesto/ios_version_detection

Improve iOS system version detection over #171
Updated podspec for version 1.6.5.1 (patch for Xcode 4)
All urls in the project updated to use https://github.com/CocoaLumberjack/CocoaLumberjack repository
Merge pull request #188 from dvor/updating-urls

All urls in the project updated to use https://github.com/CocoaLumberjack/CocoaLumberjack repository
DDFileLogger: log file named changed to new format - MobileSafari 2013-12-03 17-14.log
Merge pull request #191 from dvor/ddfilelogger--changing-log-file-format

DDFileLogger: log file name changed to new format
Update Travis configuration and remove `pod lib lint` for now (broken as of CocoaPods 0.28.0)
Improve support for OS X command line tools

Avoid relying in AppKit to check OS X version.
Updated cocoapods spec
DDFileLogger: fixed crash that occured in case if application name == nil
DDFileLogger: fixed comment
Merge pull request #199 from dvor/ddfilelogger--fixing-comment

DDFileLogger: fixed comment
DDFileLogger: wrapping appName for logs in dispatch_once function
Merge pull request #198 from dvor/ddfilelogger-fixing-crash

DDFileLogger: fixed crash that occured in case if application name == nil
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