(PE-1452) Allow querying for containing-class=null

Prior to this commit, you could not query for containing-class = null.
This commit provides support for querying against null, and it also
allows for other fields (property, message, file, line) to now be
queried for null.
(PE-1452) Explicitly check for nil
Merge pull request #650 from shakedown/dev/burgundy/pe1452-query-null-support

(PE-1452) Allow querying for containing-class=null
Rename all of the inconsistent files to the plural form

We had a lot of related files where some versions where named
in the singular and some in the plural.  We decided to
standardize them.  This commit simply renames the files; will
update the code in subsequent commits in hopes of preserving
diffs.
Fix all references to previously singular namespaces

Conflicts:
	src/com/puppetlabs/puppetdb/cli/export.clj
Merge pull request #647 from cprice404/maint/burgundy/pluralize-all-the-things

Rename all of the inconsistent files to the plural form
Update README links to point to v3
Rename `sourcefile` and `sourceline` to `file` and `line`

The resource endpoint was using the terms `sourceline` and
`sourcefile` to reference the manifests; other places in
the API were simply referring to these as `line` and `file`.

This commit changes the names to be consistent (`line`, `file`)
for v3, while ensuring that the old names still work properly
on the older versions of the query API.
Fix terminus code to use v3 endpoints
Fix bad url in test
Merge pull request #652 from cprice404/bug/burgundy/update-terminus-to-use-v3

Bug/burgundy/update terminus to use v3
Merge pull request #653 from cprice404/bug/burgundy/plural-catalogs-url-in-acceptance-test

Bug/burgundy/plural catalogs url in acceptance test
Add test for `export` namespace, fix require
tests: add ruby tests to travis-ci

This switches the TravisCI matrix to support different languages so we can do
tests for Clojure and for our Terminus as well for PR's.

For now this just supports the default version of Ruby that travis-ci provides
due to hassles trying to use 'rvm use' in a script. Later on we'll extend the
tooling to support this but for now having at least the default (1.9.3) tested
is going to get us further then where we are now.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge branch '1.1.x' into 1.2.x

* 1.1.x:
  (#22380) Document store-usage and temp-usage

Conflicts:
	documentation/configure.markdown
Merge branch '1.2.x' into 1.3.x

* 1.2.x:
  (#22380) Document store-usage and temp-usage
Merge branch '1.3.x' into 1.4.x

* 1.3.x:
  (#22380) Document store-usage and temp-usage
Merge pull request #654 from kbarber/maint/1.3.x/trello-rspec-tests

tests: add ruby tests to travis-ci
Use `clojure.set/rename-keys` instead of doing it the hard way
Another `clojure.set/rename` cleanup, plus fix a duplicate test