Don't let the View Admin button's icon dim when tapping.

Props @koke
Store current selection on sidebar

After some changes, `currentIndexPath` wasn't saved for items in section
0.

resolves #40
Merge branch 'release/3.7' of github.com:wordpress-mobile/WordPress-iOS into release/3.7
Fix selection restoration for sidebar
Improve how images are loaded in reader

* Reload images on rotation
* Use aspect fit when a cell image is set. This allows for the image to
  scale up/down after rotation while the right size is fetched
* Reload images when cell is displayed, since cells won't have the right
  size on creation for iPad. resolves #39
Decide to load images depending on scrolling speed

Before this, we loaded reader images only when the table wasn't
scrolling or being dragged unless we had the image ready with the
correct size. This meant that images wouldn't load if you were scrolling
really slow, or even stopped but still had your finger on the screen.

This implementation only prevents image loading if we detect the table
view is scrolling "fast".

After testing, images seem to load almost immediately on WiFi while
performance is still good. I'll have to test on 3G to see if it's good
enough.

see #24
Fixes an issue where simulating pull to refresh tripped isFastScrolling

Setting the table view's content offset, as we do when simulating pull to refresh or dismissing the refresh header, triggers the scrollViewDidScroll: delegate method.
Since the refresh offset is greater than the fast scrolling threshhold the _isFastScrolling flag is set but never cleared since the scrollview is stationary.
The result is that newly added cells do not display their featured images.
Adds a flag that we can check to see if the refresh offset is being set so we can skip setting the _isFastScrolling flag
Improves the pullToRefresh/isFastScrolling patch
https://github.com/wordpress-mobile/WordPress-iOS/commit/4a995c577c63d2fde03d8e0988b1e65d75744d46
Strip the contents of script tags from the reader post summary.
Merge branch 'release/3.7' into develop