Introduce CruUserDao and CruUserManager

@frett This is almost ready but would like you to look at something. Testing fails during 'mvn install' of ldaptive (or parent). This is because spring does not know how to autowire `UserDao` in `DefaultUserManager`, when injecting it into `AbstractDefaultUserManagerIT`, as there are now two instances to choose from (`LdaptiveUserDao` and `CruLdaptiveUserDao`). This issue also occurred within `LdaptiveUserDaoIT`, however I was able to differentiate therein by way of `Qualifier`. However, I don't want to use a `Qualifier` in non test code. 

My design also requires that two UserDao's (the same two UserDao's) be injected into`CruUserManager`, since `CruUserManager` needs a `CruUserDao`.

If you have any thoughts on different design and/or how to resolve the autowiring failure, please let me know.