Remove priorities from base filters.

 * issue logsearch/logsearch-boshrelease#58
Add defaults with prioritized filters like before.

 * issue logsearch/logsearch-boshrelease#58
Include (short) GIT_HASH in package name - logsearch-filters-common-${BUILD_NUMBER}.${GIT_HASH}.tgz
Combine filters into logstash.filter.conf during bin/build.sh - enables writing integration tests.
Package just logstash.filter.conf into TGZ
Refactor filters into snippets and update testing environment for integration tests.
New build script (build.sh src/defaults.conf.erb) and test script (build-and-test.sh)

Issue #16
Refactor build and test to ensure they're reusable.

Issue #16
Simplify logstash.lib.sh sourcing.
Merge pull request #16 from logsearch/refactor-filters

Refactor filters