Append any initialization options to the generated initialization output

Resolves #8 by appending initialization to the rest of the initialization code

Example buildout.cfg section
```
[gae_tools]
recipe = appfy.recipe.gae:tools
sdk-directory = ${gae_sdk:destination}/google_appengine
initialization =
    import dev_appserver
    dev_appserver.fix_sys_path()
extra-paths =
    ${buildout:gae-deploy-dir}
    ${buildout:gae-deploy-dir}/dist
    ${buildout:directory}/local_appserver_deps
```