Fix default log file directory
Fix default log file directory

Used cache directory instead of Application Support so that the log files will not get backup.

#2292

couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios,couchbase/couchbase-lite-ios