terraform_tflint: Fix files array assignation

[maxbrunet]

Files were concatenated into a single space-separated string

How args are passed to the tflint function might have to be improved too.

Here's shellcheck output:

$ shellcheck terraform_tflint.sh                                                                                                                                       [12:11:58]

In terraform_tflint.sh line 36:
    let "index+=1"
    ^-----------^ SC2219: Instead of 'let expr', prefer (( expr )) .


In terraform_tflint.sh line 43:
    tflint $args
           ^---^ SC2086: Double quote to prevent globbing and word splitting.

Did you mean:
    tflint "$args"


In terraform_tflint.sh line 534:
[[ $BASH_SOURCE != "$0" ]] || main "$@"
   ^----------^ SC2128: Expanding an array without an index only gives the first element.

For more information:
  https://www.shellcheck.net/wiki/SC2128 -- Expanding an array without an ind...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2219 -- Instead of 'let expr', prefer (( ...

[maxbrunet]

Closing in favor of #77