Rename "bookmarks" to "saved pages"

Change-Id: I9c3cd87d6473738e021d77d4ef56e312aecce891
Save full text of page to filesystem.

- when the user clicks Edit on a saved page, ask to
refresh the page. If the user agrees, reload the page
from the web, update the saved copy, and allow editing.
- Deletes folder appropriately when saved page is deleted

Change-Id: I2b8bffd95dd0036859c21494917700f3a822f942
Save images of saved page

Images are stored in the same directory as the saved page.
No extra code for tracking needed, and better for consistency
vs. the database approach.
Another plus is that when we delete the saved page the
associated images are removed automatically.

Parsing of HTML is done using Html.fromHtml with a custom imageGetter.
This uses TagSoup internally, so no need to include an HTML parsing library.

When a saved page is loaded the img src URLs get replaced
by file URLs pointing to the saved image files.

Change-Id: I1c81ccefce50d5b4fe3c1790bfe803778315bd4c
Merge branch 'savedpages' into master

Change-Id: I9783b3d8aeb197305459a480873c06fb3e394649