Bug fixes and code improvements
bec220e a bit more date validation and checking, fix for tinode/webapp/issues/78
21a18da Remove unused _lastTopicUpdate
0cf8227 Move MetaGetBuilder
into separate file, fix cache timestamps
8745597 Make largeFileHelper
respect base URL
4c25f8c Fix database initialization and teardown
8396443 Move AccessMode
into a separate file