Fix r10k check

[LMacchi]

Latest R10k versions deprecated and removed the PUPPETFILE variable, making the r10k check fail. In the future there will be flags to provide that argument, but in the mean time, a dirty hack to allow the script to continue to work.

root@bitbucket /root> ./r10k_syntax_check.sh /root/my-control-repo/Puppetfile
Performing a syntax check on the r10k Puppetfile:
Syntax OK

[pillarsdotnet]

Alternatively, you can run r10k from a subshell.