#1 Compile; create tables on first access

[Steve Barber]

Fixes two problems with javaldap-0.20:
1) Code does not compile --
org.javaldap.server.ConnectionHandlerPool referenced
non-existent 0-arg constructor for ConnectionHandler.
Commented it out, because ConnectionHandlerPool is
totally unused anyway.

2) BackendJDBC creates tables only on an add attempt.
If first access to the directory is not an add, the
operation will fail, causing some LDAP clients to
hang. Fix is to check to see if the ENTRY table exists
when initializing BackendJDBC, and then call initialize
() upfront rather than lazily on the add.

[Steve Barber]

Compile & create tables on first access