Support ignoring files/dirs via the CLI

[brentlintner]

Would be helpful when recursing dirs.

Something like synt a -i *-foo.js.

Perhaps use https://www.npmjs.com/package/ignore.

[adonis-work]

I am getting this error:

~/frontend$ synt analyze --ignore '*test*' src/

  error: unknown option `--ignore'

~/frontend$ synt analyze -i '*test*' src/

  error: unknown option `-i'

~/frontend$ synt -i '*test*' analyze src/

  error: unknown option `-i'

[brentlintner]

@adonis-work not sure if this was a test on the PR for ignore or not? No worries if it was mistaken. :-)