move Create Repo and Send To F-Droid to the Options menu

refs #2454
store the IP Address and repo URL at the start so we can gen QRCodes, etc.

The IP Address is used as the repo address, which is also used for the
direct download link to fdroid.apk for bootstrapping other devices. It is
split out into its own method so that it can be called whenever the IP
address changes, i.e. when the device connects to a new wifi network.

refs #2454
generate QR Codes internally based on zxing's core.jar

This app needs to be able to generate QR Codes regardless of what other
app might be installed, so zxing's core.jar needs to be embedded in this
app.

refs #2470
implement rough version of main repo screen

This is an implementation of the first screen of this:
https://guardianproject.mybalsamiq.com/projects/securemobilemessaging/Kerplapp%20main%20screen

refs #2454
if wifi is not enabled, make the repoSwitch enable wifi, then the repo

If the wifi is not enabled, then there is no IP address to get, and
therefore the repo cannot be configured.  To handle this, the repoSwitch
is turned into a switch for enabling the wifi first.  Once the wifi is
enabled, then the repoSwitch is configured to start/stop the repo.  The
repo URL is displayed in the repoSwitch, and the wifi network name is
displayed in its own text field below it.

refs #2454
generate the QRCode to fit the screen of the current device

Use the smallest of x,y to set the dimensions of the square QR Code.

refs #2454
update instructions

refs #2454
use fdroidrepo:// URI in QRCode so that Android will direct it to F-Droid

There is a merge request in to make F-Droid register to receive all
fdroidrepo:// and fdroidrepos:// URIs.  This comment makes the QR Code use
that URI so that it'll be automatically directed to F-Droid when scanned.

Here's the related merge request:
https://gitorious.org/f-droid/fdroidclient/merge_requests/39

refs #2470