Merge branch '1.7.5' into develop

Conflicts:
	core/src/main/java/com/orientechnologies/orient/core/metadata/schema/OClassImpl.java
	distributed/src/main/java/com/orientechnologies/orient/server/hazelcast/OHazelcastDistributedDatabase.java
	server/src/main/java/com/orientechnologies/orient/server/distributed/ODistributedStorage.java
	tests/src/test/java/com/orientechnologies/orient/test/database/auto/SchemaIndexTest.java