Implement ldap_test hue django management command

When Hue is integrated with LDAP, users can use their existing credentials to authenticate and inherit their existing groups transparently in Hue. Currently Hue has rich ldap settings, more that 20 different configuration variable. Often times it creates difficulty for Hue LDAP integration.

The objective of this bug is to simplify Hue-LDAP integration.

[desktop]
[[ldap]]
create_users_on_login=True
sync_groups_on_login=False
ignore_username_case=True
force_username_lowercase=True
force_username_uppercase=False
subgroups=suboordinate
nested_members_search_depth=10
follow_referrals=False
debug=False
debug_level=255
trace_level=0
base_dn="ou=huetest,DC=aaaaaaaa,DC=com"
nt_domain="aaaaaaaa.com"
ldap_url="ldap://2k12-1.aaaaaaaa.com:389"
use_start_tls=True
ldap_cert="None"
ldap_username_pattern="None"
bind_dn="hue admin"
bind_password=*******
search_bind_authentication=True
test_ldap_user="euser1"
test_ldap_group="prakashgroup"
[[[users]]]
user_filter="objectclass=user"
user_name_attr="sAMAccountName"
[[[groups]]]
group_filter="objectclass=group"
group_name_attr="cn"
group_member_attr="member"