allow bind against the current user

[vchrizz]

added to be able to use %{password} and %{username} in the LDAP omniauth initializer
credits @pscdodd #59 (comment)

[vchrizz]

@tmilewski @pyu10055 as you are gem maintainer for omniauth-ldap...
does this pull-request validate to be merged and put into the gem?
if not, what needs to be done and how could i help to do it?

[pboling]

@vchrizz
In v2.3.1 I added support for REMOTE_USER to allow single-sign-on.
https://github.com/omniauth/omniauth-ldap#trusted-header-sso-remote_user-and-friends
Does that obviate the need for this? Or is this still useful?

[pboling]

Hopefully the REMOTE_USER support will lessen the need for this. I don't plan to work on this unless the I get some sponsors for this gem. Full explanation here:
#59 (comment)