Update email and defaultBlog for default WordPress.com account

Adds a new field `email` to WPAccount model. We'll send an update request to `/me` endpoint during login, just after defaultWordPressCom account is created or updated and update the email and defaultBlog information according to it.
`getUserDetailsWithSuccess` helper moved to AccountServiceRemoteREST.

Updating the user details in login page moved into the success block of syncing the blogs for the account since we use those blogs to set the default blog.
Set email and defaultBlog in CreateAccountAndBlogViewController
Renaming methods for updating account details
Merge pull request #2977 from wordpress-mobile/issues/2972-store-extra-account-details

Update email and defaultBlog for default WordPress.com account