Get authToken from account
Migrated some WordPressComApi calls to WPAccount
Don't sync notification settings on app active
Remove calls to [WordPressComApi sharedApi]

For #22
Merge branch 'feature/22-accounts' of github.com:wordpress-mobile/WordPress-iOS into issue/22-remove-comapi-warnings

Conflicts:
	WordPress/Classes/Blog.m
	WordPress/Classes/NotificationsManager.m
	WordPress/Classes/WPMobileStats.m
	WordPress/Classes/WPcomLoginViewController.m
	WordPress/Classes/WordPressAppDelegate.m
Merge pull request #750 from wordpress-mobile/issue/22-remove-comapi-warnings

#22 Remove WordPressComApi deprecation
Remove method that was set for removal in future

If this in fact needed, it can be reverted. It was not called.
Collapse WPComApi and WPAccount notifications

For account change

#22
Use WPOAuthClient for sign in

Note @koke, that for JetpackSettingsVC, the effect of creating a new account may not be the correct approach taken. signInWithUsername:password:blocks use to store the authtoken internally within WordPressComApi. Now, the only way to save a token is by creating a new account.

We could make `refreshTokenWithSuccess:failure` useful again for these kinds of purposes.
Make WPAccount handle keychain and sign out tasks

- WordPressComOAuthClient should likely handle the keychain for auth token

- Remove kWPcomXMLRPCUrl as self.xmlrpc for a dot com blog is the same

- Collapse various const NSString keys that had the same value
Move notifications constants, add convenience
Decouple syncPushNotificationInfo

Registers and gets settings via XML RPC API
Decouple saveNotificationSettings

- Move app usage into NotificationsManager

- Make WordPressComApi app-independent
Decouple fetchNotificationSettings

- Move app usage into NotificationsManager

- Make WordPressComApi app-independent
Decouple notifications unregistration

- Move app usage into NotificationsManager

- Make WordPressComApi app-independent
Remove notification from WordPressComApi

- Notification was posted for checkForUnseenNotifications

- Also turns out that this method is called, but nothing observes the notification

- Removed the call from the app in NotificationsManager.
Decouple numerous headers from WordPressComApi

- WPToast: present toast from callers instead

- Constants, WPAccount, ContextManager, Note
Decouple Note from WordPressComApi

- Calls to WordPressComApi discovered that relied on the Notes being synced
Update Note with renames and API category

- Split out the API usage into a category for organization

- Rename confusing ‘sync’ method to `mergeNewNotes:` like other models
Method name change

- checkNotifications -> fetchRecentNotifications; fetches the last 20