Added an AboutScreen Property

Added an AboutScreen property for info that will be shown in the
system menu. Created a new property editor, TextArea, for long texts
Clarified the Notifier documentation for ShowChooseDialog and
ShowMessageDialog

Change-Id: I08efe7db25d715e1728fcdca9cae5795192c0214
Added more <users-features> to the Companion

This should result in the Google Play Store showing the Companion to
Tablet users.

Change-Id: I8eb2db1786adce86d61885c39cb881013f3dc419
Properly Handle Reading Larger Files from GCS

The Google Documentation shows reading GCS files with one read() call
to an open file channel. However on App Engine the read() call may
return fewer bytes then the file contains in which case you have to
call it multiple times until all data is read. Assuming this change
fixes the problem with have with files larger then 8MB, we will submit
a bug report for the GCS/App Engine documentation.

Change-Id: I58d982d0f36932121d5ccb91d0400aabb55c1536
Enhanced Companion: Can now scan and load APK files.

When you package an app and generate a QR Code, you can now use the
Companion to scan that code and it will call the package
installer. This means that you no longer need an external bar code
scanner to install packaged files from App Inventor. The Companion
provides you all that you need!

Also fixed #520. If you start the Companion when you don’t have a WiFi
connection, you will receive an Error Dialog box after which the
Companion will exit. No WiFi connection is needed for a USB
connection.

Change-Id: Ia0d96b1a7e49fd6e3fc5801ad86c9124adbe0a71
Make the font for the Companion Connect code larger

Change-Id: I83d1d211b0cfebdfa8f26ca9f912dd9e4fe5cadb
Fix Minor Component documentation regression

Change-Id: Iae34c6363d3312746d9efff18fb3891d2746723b
Update Companion Version Number (2.15ai2)

Change-Id: I62d242b6662326ab1a0f872e220f9c64769a3789
Add 2.15ai2 as an acceptable companion version

Change-Id: I106a6a4664701a268c6972e45ad63fd4b405d70d
Fix eval_but_ignore and add unit test

Change-Id: Ibb180528bf7496027b263ad59db5675129e2c0d8
Extended Notifier to allow some HTML formatting in alert messages

Extended Notifier to allow some HTML formatting in alert messages
Added AboutScreen property that lets developers provide information
about their apps. Updated refereence documentation.

Change-Id: Ic81e0554f586048f3cf83b53904b2d85aa65ec8f
Update ACCEPTABLE_COMPANIONS to only accept current Companion.

Change-Id: Ia54caa8bba335a213730bdae01fe624c5b09e0e9