Update Companion Version to 2.21ai2

Change-Id: I4f37f388e80a490dc7d87d55bd2fcc926841e429
Set minSdk back to 3. This removes support for screen density settings.

Set back minSdK to 3. Removes tablet densities. We need to better
understand how to make this change correctly so Canvas, Balls and
Sprites behave properly.

Change-Id: I22d514866c2b31fd0132c563818e6d94ab67a51d
Update Companion Version to 2.22ai2.

Change-Id: Icecf2daad3064c28a644221143a7e8d190f28b83
Changes the word 'Digit' for 'Character' in the Companion textbox hint
Arrange for Companion to report its package name.

Arrange for Companion to report its package name, this permits the
service to determine if the correct companion is being used. This is
of particular value to people compiling their own version of App
Inventor and want to make sure their end-users are using the
corresponding Companion. The code to check the package name in the
service is not yet written, this change is just on the Companion side
to report its package name along with its version.

Change-Id: If1b9624ab60830b336bac8122eb8dbb9fb34a167
Bugfix to templates

Change templateHostUrl to be non-static so it updates when you switch
between different templates.

Change-Id: I65969fef011e428a906b622855dbc1fbc1b66e70
Fixes race condition that caused duplicate template projects to be created.

Change-Id: I8907001091444f0c4d5004b76ad3b2cb5ecb08b0