Remove test module
Fix security vulnerability

As discussed in #8 Googles implementation of the In-app-billing sample has some serious security flaws. This commit applies the suggested fixes https://code.google.com/p/marketbilling/source/detail?r=7bc191a004483a1034b758e1df0bda062088d840.
Switch to generally available robolectric version 2.2 since there is no need to use the possibly unstable SNAPSHOT
switch to aar
update version
fix NPE when IabHelper has been destroyed while a query is running
fix another NPE when IabHelper has been destroyed while a query is running
increase version
Fix build
Merge remote-tracking branch 'patch/patch-1' into sprylab

Conflicts:
	library/src/main/java/com/github/jberkel/pay/me/IabHelper.java