build a local repo from a list of installed APKs
Wire up the "Setup Repo" button on the Local Repo view to generate an
FDroid repo on the device that is hosted with the local webserver. This
also generates an index.html for when people navigate to the local repo via
a browser. This index.html will allow them to both download FDroid and to
setup the repo on the device running the webserver on the local FDroid.