fix #1139: call RefreshBlogContentTask on first blog when user login

fix #1139 

* call RefreshBlogContentTask on first blog when user logins
* call RefreshBlogContentTask when user adds a self hosted blog
* call RefreshBlogContentTask on blog changed
* remove calls to RefreshBlogContentTask in PostsActivity
parseInt() will throw a NumberFormatException here in the unlikely (but not impossible) chance that blogId isn't an integer. You can use StringUtils.stringToInt() to avoid this problem.