Support more complicated path_regexp

[sfrevel]

Is it possible to support more complicated regexp in path_regex? Like mentioned in the documentation here https://golang.org/pkg/regexp/#MatchString

"More complicated queries need to use Compile and the full Regexp interface"

so the match has to be implemented more like this

validRegExp = regexp.MustCompile(path_regexp)
match = validRegExp.MatchString(filePath))

I think this is the reason for issues like this one #480

We also had problems to specify a path which is including the filename and not just a filename. Especially if there are '/' in the path it's not working at all and we get the message 'no matching creation rules found'

Example not working (no matter if '/' are escaped or not!):

path_regexp: stages/dev/secrets.env$

Examples working:

path_regexp: .*dev.*
path_regexp: secrets\.env$

[autrilla]

We would be happy to take a patch for this. An accompanying test to show the improvement would be excellent too.

[bcolucci]

#829