Fix #2581 Close WAL when DB is closing

(cherry picked from commit b1d207ffcaa77b25aa87aad744329f8b4c1a667a)

Conflicts:
	core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/OAbstractPaginatedStorage.java
	core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/paginated/wal/ODiskWriteAheadLog.java