Added initial calls to record details of file downloads.

This is a work-in-progress.
Storing my additions to the Constants before merging the changes from the team.
Merge branch 'master' of https://github.com/julianharty/new-android-daisy-reader

Conflicts:
	DaisyBookLister/src/org/androiddaisyreader/utils/Constants.java

I have merged the conflicts in Constants.java to reflect both sets of changes.