Allow both text and media to be shared to the post editor at the same time. Previously we were only accepting text OR media. Why not both? Fixes #180.
fix #499: show an error message and close the picker activity if there is no media after refreshing from server
Check for image and video type before processing a single attachment, as it could be a different type of stream like text.
fix #553: media date filter refreshes when blog change
Merge branch 'issue/498-empty-media-view' into issue/553-media-custom-filters-refresh

Conflicts:
	src/org/wordpress/android/ui/media/MediaGridFragment.java
fix #559: don't display the share view with one blog and text

* fix a NPE when user doesn't have visible blog
* if the user isn't signed in, redirect it to the login screen, if he's signed and have no visible blog, display a toast error and finish the share activity
* move isSignedIn to Worpress.java
Merge pull request #539 from wordpress-mobile/issue/180-share-text-and-media-fix

Allow both text and media to be shared to the post editor at the same time.
Merge pull request #565 from wordpress-mobile/issue/559-unnecessary-share-view

fix #559: don't display the share view with one blog and text
fix #549: add option to remember last share selection

* add checkbox in share view to remember last share selection.
* this checkbox saves state differently for text shares and image shares.
* add a "reset auto-sharing settings" in preference view.
* if the select blog id doesn't exist anymore (or is hidden), auto-sharing settings will be reset, the user notified by a toast message.
Merge branch 'develop' into issue/549-add-option-to-remember-last-share-selection
Merge pull request #562 from wordpress-mobile/issue/499-empty-media-picker-when-no-media

fix #499: show an error message and close the picker activity if there is no media after refreshing from server
change checkbox style to match the dark background
Merge pull request #563 from wordpress-mobile/issue/553-media-custom-filters-refresh

Fix #553 media custom filters refresh
better wording
Merge pull request #570 from wordpress-mobile/issue/549-add-option-to-remember-last-share-selection

Fix #549: add option to remember last share selection
Merge branch 'develop' into issue/311-confusing-error-dialogs

Conflicts:
	res/values/strings.xml