Sync wiki submodule
Add comment re: NEW_RELIC_APP_NAME assignment bug

See #262
Reduce the number of indexer instances from 4 to 1

There is no need to run 4 indexer instances; indeed, doing so is
undesirable when considering that any number greater than 1 instance
results in competetion without coordination, meaning the same content
gets indexed and re-indexed for no reason and with no benefit.
Revert "Add Disqus comments to blog posts"

This reverts commit 38565e10abb403c9371318b626d05738b08f2f24.
(Unintentionally committed)
Support -Pspace=<...> vs. -Pproduction / -Pstaging

Prior to this commit, deployment required specifying

    ./gradlew deploy -Pproduction # OR
    ./gradlew deploy -Pstaging

This worked fine, but required unnecessarily complex conditional logic
in deploy.gradle. This change refactors this logic such that -Pspace is
required and the value is treated as the target space. 'production' is
treated as a reserved value and gets special treatment, e.g.:

 - 'panda' database instead of default 'hippo'
 - 'spring.io' and 'www.spring.io' URIs are mapped, instead of the
   default '${space}.spring.io'

If the value of the space property is anything other than 'production',
then the defaults mentioned above apply instead.

If the space property is not present and the build is running on Travis
CI, the implementation now looks to the name of the current git branch
to determine the target space. This allows us to push changes to master
in order to deploy to production, and to push branches named stage-foo,
stage-bar, etc to deploy to staging.

See also #331
Make fields private where possible
Add Disqus comments to blog posts

Per instructions at
http://spring-io.disqus.com/admin/settings/universalcode, three 'sites'
have been set up at Disqus under the 'saganops' account:
 - spring-io (production)
 - spring-io-staging
 - spring-io-localhost

Depending on the active Spring profile (see changes to application.yml),
one of these names will be exposed to the frontend via BlogController as
'disqusShortname'. See changes to _full_post.html to see where this is
assigned to disqus_shortname.

Comment threads are correlated with individual posts using
disqus_identifier, which is assigned the (unchanging) database id of the
post being rendered.