Lets the user decide how big the font size should be for an article.

Added an item to the menu article_view.xml so the user can select the font
size.  Shows a dialog box with three options:  small, medium, and large.
Also I deleted the search option in the article_view.xml because the user
doesn't need that in an article view.  Strings.xml was changed to
accommodate new strings.
Cleans up ArticlesViewed file on the device after 80 articles have been viewed.  Reduces the number to the most recent 40 articles.
App displays the font change button in the action bar.

Added font-size-change icon to the action bar.  Made it save the font size
within a session.
Added .pngs for font size
Merging origin into testingBranch
Merge pull request #18 from Flauschig/testingBranch

Testing branch