Ldapadmin testsuite

This PR aims to leverage a bit the test coverage specifically on the LDAPAdmin application. After applying these commits, the global test coverage increases from 19% to 73%. In addition, some minor modifications have been made, related to using Apache DBCP and the configuration/build process.

Even if the goal is to make sure further developments won't imply regressions, some manual tests have been made:


- User
  - [x] Create
  - [x] Update
  - [x] Delete

- Group
  - [x] Create
  - [x] Update
  - [x] Delete

- User / Group
  - [x] Affectation
  - [x] De-affectation

- [x] Lost Password

Note: exim was misconfigured on my computer, but the mail has been frozen in the exim4 queue, after checking, it was correctly sent by the webapp.

- [x] New account

Note: same remark, both "welcome mail" and "mail to warn the useradmin" were sent.