[SPARK-2608] fix executor backend launch commond over mesos mode

[scwf]

https://issues.apache.org/jira/browse/SPARK-2608
This is the updated version of #1513

Mesos scheduler backend use spark-class/spark-executor to launch executor backend, this will lead to issues:
1 when set spark.executor.extraJavaOptions CoarseMesosSchedulerBackend will throw errors because of the launch command "./bin/spark-class org.apache.spark.executor.CoarseGrainedExecutorBackend %s %s %s %s %d").format(basename, extraOpts, driverUrl, offer.getSlaveId.getValue,offer.getHostname, numCores))

2 spark.executor.extraJavaOptions and spark.executor.extraLibraryPath set in sparkconf will not be valid

[AmplabJenkins]

Can one of the admins verify this patch?

[tnachen]

Is there any difference between this PR than the one you closed?

[scwf]

@tnachen, no actually, i just merge with the new master

[liancheng]

Only passing sc.executorEnvs here to the command object here is not enough. Because we only use command with CommandUtils.buildCommandSeq below to generate the command line string, and in this case, command.environment is only used to run bin/compute-classpath (see here), not propagated to the target executor process.

[scwf]

yes, here i should set env to CommandInfo to propagate to the target executor process.

[andrewor14]

Hi @scwf, given that there is another PR that supersedes this one, would you mind closing this? There are many duplicates of the same PR and it's a little confusing to find that all of them are open.