(PDK-397) Log output of bundler commands at appropriate levels

[scotje]

Output of bundle check should go to DEBUG but non-zero exit status for the rest of the bundler commands represent fatal errors.

[coveralls]

Coverage decreased (-0.02%) to 93.677% when pulling 7cf2d71 on scotje:397_hide_bundle_check_output into 29937f8 on puppetlabs:master.

[scotje]

Coveralls failure is because there was a net decrease of 5 lines in a covered file, coverage of that file is still 100% of relevant lines...