isAutoIncrement - verify if LiquibaseDataType has auto increment
property
set index name for DropIndexChange - fixed issue with
dbchangelog-3.1.xsd - element dropIndex,  attribute indexName
Merge branch '3.1.x' of https://github.com/justcoon/liquibase into justcoon-3.1.x

Conflicts:
	liquibase-core/src/main/java/liquibase/util/ObjectUtil.java
Merge remote-tracking branch 'origin/master'