use the RegisterPlugin function instead of manipulating AvailablePlugins directly, and get rid of the silly plugin_loader.go.in setup.
Move the plugin init into the pipeline package so the tests will still run.
re-add plugin_loader.go to .gitignore since heka-build might generate it.
update install notes to refer to heka-build and better 'go get'
Merge pull request #23 from mozilla-services/features/register-plugins

Features/register plugins
add date for supported go revision
more idiomatic default config location
don't swallow error messages
set the outBatch index as appropriate
Fix the log file writer to actually copy and output the data correctly.
Don't try to use an outData object if prepOutData returned an error.