LIVY-356 Enabling LDAP authentication for Client to Server.

[jakhani]

Currently, Livy doesn't support LDAP Authentication from client(sparkmagic) to server(livy). We need to add LDAP authentication as that's preferable method due to security reasons. We won't be able to use Knox for this purpose. That is why I am raising this PR which contains LDAP authentication.

I am also adding config to disable batch endpoints. Due to security reasons, we don't want to keep batch endpoint open. I am adding config so that We can disable it.

[codecov-io]

Codecov Report

Merging #343 into master will decrease coverage by 1.37%.
The diff coverage is 13.63%.

@@             Coverage Diff              @@
##             master     #343      +/-   ##
============================================
- Coverage     70.63%   69.25%   -1.38%     
- Complexity      730      732       +2     
============================================
  Files            96       97       +1     
  Lines          5153     5283     +130     
  Branches        776      796      +20     
============================================
+ Hits           3640     3659      +19     
- Misses          996     1105     +109     
- Partials        517      519       +2

Impacted Files	Coverage Δ	Complexity Δ
...er/src/main/scala/com/cloudera/livy/LivyConf.scala	94.61% <100%> (+0.26%)	16 <0> (ø)	⬇️
...in/scala/com/cloudera/livy/server/LivyServer.scala	34.44% <15.78%> (-2.98%)	9 <0> (ø)
...vy/server/auth/LdapAuthenticationHandlerImpl.scala	8.41% <8.41%> (ø)	0 <0> (?)
.../java/com/cloudera/livy/rsc/driver/JobWrapper.java	80.64% <0%> (ø)	8% <0%> (+1%)	⬆️
...n/java/com/cloudera/livy/rsc/driver/RSCDriver.java	78.87% <0%> (+1.29%)	42% <0%> (+1%)	⬆️

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[jakhani]

@jerryshao Can you please review this PR? I have discarded old PR for LDAP as this is better solution.

[jerryshao]

Sorry @jakhani for the delay, we're working on migrating Livy project to ASF, It would be better to wait for while and send PR against in new repo. Really sorry about the delay.

[jerryshao]

Hi @jakhani can you please submit this PR against incubator-livy (https://github.com/apache/incubator-livy/pulls), thanks!

[jakhani]

@jerryshao I will raise PR and let you know. Thanks.