AC-63 Some issues with OpenMRS logo

Updated OpenMRS icon for launcher, application log in screen at mdpi,
hdpi, xhdpi, xxhdpi, and xxxpdpi resolutions, as well as replaced Play
Store launcher icon.
Merge pull request #46 from openmrs/AC-63

AC-63 Some issues with OpenMRS logo
AC-24 - [Test] Add Login Activity test
AC-41 [Test] Add Logout test
AC-25 - [Test] Add Find Patients Details test
AC-25 Improve test