Documentation for distributed deployment and schedulers (apache#747)

* added initial scheduler documentation

* Documentation for Deployment Overview and configuration. Also modified Aurora Cluster, Mesos Cluster, Local Cluster and Slurm Cluster

* incorporated feedbacks on English corrections

* empty new line at the end

* incorporate feedbacks on English

* incorporate additional feedbacks

* removed setup from toc

* fixed feedbacks

* change mdash to use ---

* reworded text and removed the link

add serialVersionUID for TestWordTopology (apache#718)

implement aurora scheduler getJobLinks (apache#707)

commit messages should be enclosed in quotes (apache#642)

fixed several docs

Shut down all executor services in SchedulerMain when killing a topol…

…ogy (apache#520)

Shut down all executor services in SchedulerMain when killing a topology.

Merge pull request apache#257 from twitter/karthik/docs

Updated getting started guide

Merge pull request apache#241 from twitter/karthik/ps

added ps command

Release 0.13.1-C (2016-03-23)

Baseline: 411dcb7
   + 0e90a76: change python module import from heron.common to
              heron.tracker
   + 32e5b9f: SubmitterMain: move to using commons cli arg parsing

Release 0.13.1-C (2016-03-23)

Release 0.13.0-C (2016-03-09)

Baseline: b9a2997
   + 7f42fb9: Move constant "HERON_SYSTEM_CONFIG" from misc.Constants
              to class com.twitter.heron.common.config.SystemConfig

Release 0.13.0-C (2016-03-09)