Remove error handling notifications

- Show appropriate alert from where the error occurs
Merge errors in AppDelegate with WPError

- Launch Support from WPError through SupportViewController on the tab bar
Merge branch 'issue/609' into issue/627
GPL headers for WPError
Use new WPError methods for ‘Need help’ alerts

- For some the support button is added as it probably makes sense to do so

- Give the option to disable the support button

- Documentation
Introduce custom actions for OK pressed on alerts

- A block that allows for custom actions if the OK button is pressed
Fix error handling and use WPError for EditSite

- Use the OK block for sending the user to their site

- Fixes the 405 error handling as it was always −1011 instead of 405. Tested with Charles proxy.
Fix error handling and use WPError for WPTableVC

- Use the OK block for sending the user to their site for XML RPC error

- Fixes the 405 error handling as it was sending −1011 instead of 405. Tested with Charles proxy.
Fix test compilation
Use WPError for almost all alerts

- Most alerts follow the same standard pattern.

- By default, show the Need Help? button, so users experiencing repetitive errors have a chance to contact WP about them

- Very few alerts are “user choice” alerts. Leaving those alone for now, so we don’t have more signature.
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/627

Conflicts:
	WordPress/Classes/AddUsersBlogsViewController.m
	WordPress/Classes/EditSiteViewController.m
	WordPress/Classes/JetpackSettingsViewController.m
	WordPress/Classes/PostSettingsViewController.m
	WordPress/Classes/WPTableViewController.h
	WordPress/Classes/WPTableViewController.m
	WordPress/Classes/WPWebViewController.m
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/627

Conflicts:
	WordPress/Classes/Blog.m
	WordPress/Classes/EditSiteViewController.m
	WordPress/Classes/PostMediaViewController.m
	WordPress/Classes/WPTableViewController.h
	WordPress/Classes/WordPressAppDelegate.h
	WordPress/Classes/WordPressAppDelegate.m
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/627

Conflicts:
	WordPress/Classes/AddUsersBlogsViewController.m
	WordPress/Classes/EditSiteViewController.m
	WordPress/Classes/ReaderPostDetailView.m
	WordPress/Classes/WPTableViewController.h
	WordPress/Classes/WordPressAppDelegate.h
	WordPress/Classes/WordPressAppDelegate.m
Merge branch 'develop' of github.com:wordpress-mobile/WordPress-iOS into issue/627

Conflicts:
	WordPress/Classes/CommentViewController.m
	WordPress/Classes/EditCommentViewController.m
	WordPress/Classes/EditPostViewController.m
	WordPress/Classes/PostMediaViewController.m
	WordPress/Classes/ReaderCommentFormView.m
	WordPress/Classes/ReplyToCommentViewController.m
	WordPress/Classes/WPAddCategoryViewController.m
	WordPress/Classes/WordPressAppDelegate.h
	WordPress/Classes/WordPressAppDelegate.m
Merge pull request #708 from wordpress-mobile/issue/627

#627 Handle errors consistently