Only run tests on API levels where they are supported.

[JakeWharton]

This also contains some fixes for problems found on older APIs:

• equals is missing for PointF, RectF, etc.
• TransitionManager.endTransition isn't available on 19
• Bundle and PersistableBundle added support for types on various API levels.

For whatever reason the ShaderTest crashes on API 23 and 24. Everything else is good though:

Starting 235 tests on Nexus_4_API_15(AVD) - 4.0.4
Starting 260 tests on Nexus_4_API_17(AVD) - 4.2.2
Starting 289 tests on Nexus_4_API_19(AVD) - 4.4.2
Starting 300 tests on Nexus_4_API_21(AVD) - 5.0.2
Starting 304 tests on Nexus_4_API_23(AVD) - 6.0
Starting 304 tests on Nexus_4_API_24(AVD) - 7.0
Starting 370 tests on Nexus_4_API_26(AVD) - 8.0.0

androidx.graphics.ShaderTest > testTransform[Nexus_4_API_23(AVD) - 6.0] FAILED
Test failed to run to completion. Reason: 'Instrumentation run failed due to 'Native crash''. Check device logcat for details
Tests on Nexus_4_API_23(AVD) - 6.0 failed: Instrumentation run failed due to 'Native crash'

androidx.graphics.ShaderTest > testTransform[Nexus_4_API_24(AVD) - 7.0] FAILED
Test failed to run to completion. Reason: 'Instrumentation run failed due to 'Process crashed.''. Check device logcat for details
Tests on Nexus_4_API_24(AVD) - 7.0 failed: Instrumentation run failed due to 'Process crashed.'

Closes #114.