reworked migrations to fix major issue with migration system on new installs
switched testing plugin to something that is not deprecated
Merge branch 'master' of https://github.com/emilsjolander/sprinkles

Conflicts:
	library/src/main/java/se/emilsjolander/sprinkles/Migration.java
	library/src/main/java/se/emilsjolander/sprinkles/ModelInfo.java
	library/src/main/java/se/emilsjolander/sprinkles/annotations/Unique.java
	library/src/test/java/se/emilsjolander/sprinkles/MigrationTest.java
	library/src/test/java/se/emilsjolander/sprinkles/ModelInfoTest.java
	library/src/test/java/se/emilsjolander/sprinkles/annotations/UniqueTest.java
added readme for new migrations