Fix duplicate assets in apk file

For desktop, asset files were copied into common/target instead of
desktop/target, resulting in duplicate resources inside apk file. This simple
directory move solves this issue.
Avoid using spaces in names

This change avoids spaces in file names, that were created if space was
included in game name. Now, all references to game name in files are
normalized (lowercase, with hyphens instead of spaces). Also, I made sure that
assembly and apk files get correct names set both as files, and internally
(instrumentation tests were overwriting main game).
Merge pull request #30 from aginiewicz/spaces-in-names

Avoid using spaces in names
Merge pull request #29 from aginiewicz/duplicate-assets

Fix duplicate assets in apk file