Upgrade net-ldap for fix for LDAP Controls.

https://bugzilla.redhat.com/show_bug.cgi?id=956833

net-ping at 1.5.3 required net-ldap at ~>0.2.2, so we need to upgrade net-ping also.

See: https://github.com/ruby-ldap/ruby-net-ldap/pull/18

In upgrading from 0.2.2 to latest, 0.7.0, the change we need is here:
https://github.com/ruby-ldap/ruby-net-ldap/compare/v0.2.2...v0.7.0#diff-724e0b3130dc49ca34eadc7c25d28b18R1647.
We want to be able to compact any nil control_codes.
Merge pull request #505 from jrafanie/upgrade_net_ldap

Upgrade net-ldap for fix for LDAP Controls.