Add exploit for ajsif vuln in Adobe Reader.

* This refactors the logic of webview_addjavascriptinterface into a mixin (android.rb).
* Additionally, some behavior in pdf.rb had to be modified (in backwards-compatible ways).

Conflicts:
	lib/msf/core/exploit/mixins.rb
Remove extraneous method from pdf.rb
Add better interface for specifying custom #eol.
Revert change to trailer(). Kill dead method.

* I verified that changes to PDF mixin do not affect any older modules that
generate PDF. I did this by (on each branch) running  in irb, then
running the module and diffing the pdf's generated by each branch. There were
no changes.
Compress and base64 data to save bytes.

Reduced file size from 43kb to 12kb, yay.
Correct the disclosure date.
Remove lie in comment.
Remove spaces at EOL.
Land #3418 - android adobe reader addjisf pdf exploit

Merge branch 'landing-3418' into upstream-master