Analytic/tracking events class has been externalized.

Now you should be able to customize just the BakerAnalyticsEvents.m file to manage remote analytics.

Currently supports the following events:
. BakerApplicationStart
. BakerIssueDownload
. BakerIssueOpen
. BakerIssueClose
. BakerIssuePurchase
. BakerIssueArchive
. BakerSubscriptionPurchase
. BakerViewPage
. BakerViewIndexOpen
. BakerViewModalBrowser

Tested on Google Analytics.
Merge remote-tracking branch 'origin/master' into ios7