Animators defined in XMLs should work with Build Tools 22

[serso]

Problem: Build Tools 22 removes attributes targeted to higher versions of Android from xml file, copying the original file to an appropriate bucket. On lower versions of Android (f.e. 9) NineOldAndroids can't access such attributes (as they are now in animator-vXX bucket) and crashes.

Solution: let's use our own custom attributes instead of Android attributes. All XMLs defining animators should be changed - project namespace should be used instead of Android one.

Fixes #80