Update .gitignore file

1) We need to ship metadata.json with puppet modules because of
deprecation of Modulefile:

https://docs.puppetlabs.com/puppet/latest/reference/modules_publishing.html

DEPRECATION WARNING As of Puppet 3.6 the Modulefile has been deprecated
in favor of the metadata.json file.

Some modules already have no Modulefile and it's impossibleto check
such module's source/dependencies since we ignore metadata.json

2) We're going to use 'bundle' in our CI. So in order to run some
CI tests localy in the working dir it would be convenient to ignore
.bundled_gems directory that will be created by CI scripts.

Change-Id: I5523e84480ef3638a5442ac683d5e648d9f8a0fd
Merge "Update .gitignore file"