add fantasy swipe hint.
create zhihu plugin package.
add zhihu fantasy item metadata.
add zhihu items processor.
complele zhihu contentprovider.
add another `has_read` column in zhihu item.
compelete zhihu items layout code.
add zhihu items refresh and load more funcs.
change zhihu items' s time to the author.
add auto fetch func when no items at all.
bug fix.

1. fix actionbar default icon will make all preference icon change, so drop it.
2. fix zhihu item click mark `has_read` not work.
3. fix zhihu item digest when there' s image, drop it.
4. ...
complete zhihu item layout.
add quick return layout for zhihu reader.
compelete zhihu images stuff.
redesin for zhihu' s item.

use regex to spilt the text and image and insert to the scrollview.
compelete zhihu item' s images viewing.
add anim to plugin fragment transaction.
simply compelete zhihu pager item.
improve stability.

1. when showing zhihu' s image, it might huge, must resize it.
2. when using viewpager to show the answer detail, sometimes oom, so drop it for now...
3. replace some icons
add a alt option for swipe gestrue to read zhihu.