Created free version

Free version lacks dropbox and location reminders. Gtask sync
still works.

To build the free version, one needs to do:

    ./gradlew installFreeDebug

versus the non free versions:

    ./gradlew installPlayDebug
    ./gradlew installPlayBetaDebug

fixes #269

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>
Update readme with flavors types

Signed-off-by: Jonas Kalderstam <jonas@kalderstam.se>