ldap: fixed a couple of bugs around SSL support

[mssola]

This commit fixes a couple of bugs present in both master and 2.3:

1. We didn't implement some options that needed to be passed to the LDAP
   backend to fully support SSL connections. This has been addressed
   also in the configuration, but without breaking existing
   installations (e.g. the method attribute from 2.3 has been left
   untouched). This will be addressed in later commits of the master
   branch (so in 2.4 users should adapt to this change).
2. We were relying on Devise's translations for failures, but some of
   them were not available. This has been addressed and improved: the
   error message will be more on point and more informative to end
   users.

There is still room for improvement, but we can do it in later commits:
let's keep this commit to the point so it can be cherry-picked into the
2.3 branch.

Fixes #1746
Fixes #1774

bsc#1073232

Signed-off-by: Miquel Sabaté Solà [email protected]

[mssola]

Note that I've left lots of TODOs here and there, as reminders of changes that I've planned (plus some other ones). I'll do it in other PRs, since now I want a commit that can be cherry picked into the 2.3 branch.

I haven't tested this commit on top of the 2.3 branch yet, so don't merge it (but you can review it meanwhile).

[mssola]

Tests are passing if I apply this patch into the 2.3 branch. Moreover, I've tested it locally and it also works, so I'd say it's ready to be reviewed and merged whenever you say so 😉

[vitoravelino]

I don't have knowledge around LDAP but tests are passing and code wise LGTM.

[mssola]

Cherry picked into the v2.3 branch.