SPARK-2143 [WEB UI] Add Spark version to UI footer

[srowen]

I took a very basic stab at adding the Spark version number to the UI header / footer. This is the simplest place I could think to stick it without getting into the CSS much, and this is how it looks:

Thoughts? I think it's nice to have in the UI but might need to look a little different.

[SparkQA]

Test build #23730 has started for PR 3410 at commit 74c42c2.

• This patch merges cleanly.

[ash211]

Big +1 on putting the Spark version somewhere in all the various webuis. I probably wouldn't put it that big in the header, but definitely somewhere.

[SparkQA]

Test build #23730 has finished for PR 3410 at commit 74c42c2.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

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[srowen]

Sure, I'm open to suggestions to make it subtler. This is just what the simplest thing looks like.

Smaller text in the same place? or same size but with more separation? lighter gray?
I could try to establish a footer with this info; there isn't a footer, yet.

[JoshRosen]

A footer might be nice. Maybe the text it the footer could be in a more subdued grey (and possibly darken on hover)?

[srowen]

Done, it's now a footer. I just used the simple footer example from bootstrap too, which happens to be gray as well. Nothing fancy.

[SparkQA]

Test build #23765 has started for PR 3410 at commit e9b3a7a.

• This patch merges cleanly.

[SparkQA]

Test build #23765 has finished for PR 3410 at commit e9b3a7a.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/23765/
Test PASSed.

[JoshRosen]

This seem good to me; mind updating the PR title / description to say "footer" instead of "header"?

[JoshRosen]

LGTM! I'm going to pull this into the backport branches, too.

[JoshRosen]

Doh! I just realized that my branch-1.1 cherry pick is going to break the build since prior to Spark 1.2 SPARK_VERSION was only defined in the SparkContext companion object rather than in the Spark package object. I'll push a hotfix to fix that now.