Add simple plugins smoke tester

[mikemccand]

At first I tried to fold this into dev-tools/build_release.py but I think we should (separately) refactor that into "smoke testing" from "making a release"?

So for now I just made a standalone script: this was easier, and I think we can refactor later.

It just runs mvn package and then installs ES to a tmp dir, installs each plugin using bin/plugin, then starts ES and lists the plugins to see they are all there.

It currently fails with this:

14:03 $ rm /tmp/elasticsearch_smoke_test_plugins.log; python3 -u dev-tools/smoke_test_plugins.py 
Logging to /tmp/elasticsearch_smoke_test_plugins.log
Build release bits...
Find plugins:
  install plugin analysis-icu...
  install plugin analysis-kuromoji...
  install plugin analysis-phonetic...
  install plugin analysis-smartcn...
  install plugin analysis-stempel...
  install plugin cloud-aws...
  install plugin cloud-azure...
  install plugin cloud-gce...
  install plugin delete-by-query...
  install plugin lang-javascript...
  install plugin lang-python...
Start Elasticsearch
ES: [2015-06-30 14:05:05,486][INFO ][node                     ] [smoke_tester] version[2.0.0-SNAPSHOT], pid[10429], build[a847dd2/2015-06-30T18:04:00Z]
ES: [2015-06-30 14:05:05,486][INFO ][node                     ] [smoke_tester] initializing ...
ES: [2015-06-30 14:05:05,550][INFO ][plugins                  ] [smoke_tester] loaded [lang-python, analysis-kuromoji, analysis-smartcn, cloud-gce, analysis-stempel, cloud-aws, delete-by-query, analysis-phonetic, cloud-azure, lang-javascript, analysis-icu], sites []
ES: [2015-06-30 14:05:05,570][INFO ][env                      ] [smoke_tester] using [1] data paths, mounts [[/ (/dev/mapper/haswell--vg-root)]], net usable_space [210.6gb], net total_space [465gb], spins? [no], types [btrfs]
ES: {2.0.0-SNAPSHOT}: Initialization Failed ...
ES: - ExecutionError[java.lang.NoClassDefFoundError: org/apache/lucene/analysis/cn/smart/SmartChineseAnalyzer]
ES:     NoClassDefFoundError[org/apache/lucene/analysis/cn/smart/SmartChineseAnalyzer]
ES:         ClassNotFoundException[org.apache.lucene.analysis.cn.smart.SmartChineseAnalyzer]
ES: **process exit**

Traceback (most recent call last):
  File "dev-tools/smoke_test_plugins.py", line 145, in <module>
    raise RuntimeError('ES failed to start')
RuntimeError: ES failed to start

[rmuir]

+1, pls push this! we can dig into any issues as a followup.

[rmuir]

the first part of debugging whatever is happening there, will be to ensure we get a proper goddamn stacktrace!

[dadoonet]

IMHO with the distribution modules coming, smoke tests should be considered as integration tests for each artifact type we generate.

Something we should found in src/it/resources for example in each module...

[rmuir]

That won't work in this case @dadoonet

Here we are actually testing what comes out of the maven-assembly plugin, and what happens when you run bin/elasticsearch (shell scripts etc). All of these contribute to jar hell in their own special ways.