Fixes checkstyle errors in bookshelf sample.

I modify the checkstyle config to have SAME_PACKAGE imports appear
before third-party imports. I think this better matches the intent of
the import ordering rules in the style guide.
https://google.github.io/styleguide/javaguide.html#s3.3.3-import-ordering-and-spacing
Expecially since it says the `com.google` imports only appear after
static imports if the source file is in the `com.google` package space.

…ls into lint

* Moved some checkstyle modules to java-repo-tools
* Moved some lines in .gitignore to the top level

Also update checkstyle to allow 1-letter variable names, since it
doesn't make sense to give long names to something like "arbitrary
column A that doesn't actually mean anything".

Samples are moved from:
https://cloud.google.com/appengine/docs/java/datastore/indexes

Note: I add a new script `test-devserver.sh` to the testing config. This
script runs the `mvn appengine:devserver` plugin, waits for it to start,
then verifies that it gets a non-error response from the `/` path. I use
this to verify that the `datastore-indexes.xml` files are correct (by
disabling autoGenerate, the local devserver throws an error when a query
is used without the correct index defined, just as production does).

We should probably add any "hello world" or other projects to this
check, as well. Anywhere we say to run `mvn appengine:devserver`, it
would be good to test that it is correct.

…e-from-java-docs-samples

Java repo tools update from java docs samples

This should make it easier to push upstream and pull downstream.

…ls into tswast-update-java-repo-tools

This script will allow us to run tests against a local server for
testing. Since the App Engine and Jetty server running and testing is so
similar, I combined the scripts rather than copying. The only
differences are which plugin to use and what string to wait for before
running curl.

Since the bookshelf sample also needs a `-Plocal` profile argument, I
extended the script to allow passing through arbitrary arguments to
Maven.

Run the local servers and verify they respond with code 200 to the "/"
path.

Note: bookshelf does not yet run in Travis, since we'll need to set up
client secrets credentials.

…ls into tswast-push-java-repo-tools

Also, update the README instructions for how to push changes upstream.

…-tools

Update java-repo-tools from getting-started-java.

…ls into tswast-pull-java-repo-tools

Added in
GoogleCloudPlatform/getting-started-java#92