Custom string substitutors functionality

[drapostolos]

As requested here are the unit test for such functionality (plus the necessary implementation to compile). If this functionality is approved, then I'll modify this pull request with an actual implementation.

/Alex

[drapostolos]

My use case for this is:

I want to create a unique directory path, where I can place logs gathered during automatic tests. I.e. a unique folder for each test run. I would like to be able to specify this path in my configuration file, something like this:
logDirPath = ${user.home}${file.separator}${date:yyyyMMdd-HHmmssSSS}
which in practice will result in something like this:
C:\Users\alex\20141018-163934471
C:\Users\alex\20141018-164011056

My Config class will be instantiated once per test-run where the ${date:yyyyMMdd-HHmmssSSS} represents the (approx) date/time when it was constructed. Each call to the logDirPath() on the same instance must return the same value (so the same folder path is used everywhere in my code base).

/Alex

[drapostolos]

Implementation of this feature is now added. Comments?

[coveralls]

Coverage increased (+0.13%) when pulling 787b5f8 on drapostolos:string-substitutor into d1b7344 on lviggiano:master.

[coveralls]

Coverage increased (+0.13%) when pulling 0768e9a on drapostolos:string-substitutor into d1b7344 on lviggiano:master.

[coveralls]

Coverage increased (+0.13%) when pulling 0768e9a on drapostolos:string-substitutor into d1b7344 on lviggiano:master.