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
So much :heart: for killing our fork!