A problem with determination of installed versions for Bower packages

[ocrest]

In the discussion of #10 (comment) was found a problem with determination of installed versions for the Bower packages, for which those versions aren't valid semvers.

If the used version (git tag) isn't a valid semver, the generated .bower.json won't contain the version field (but will contain the _release field in all cases):

bower install susy#2.2.0.beta.3

{
  "name": "susy",
 ...
  "_release": "2.2.0.beta.3",
 ...
}

and

bower install susy#2.2.2

{
  "name": "susy",
  "version": "2.2.2",
 ...
  "_release": "2.2.2",
 ...
}

UPD: If the target version of the package is set to "*" (and there are no any valid versions), the _release field will contain the last commit hash:

bower install sass-meyer-reset

{
  "name": "sass-meyer-reset",
 ...
  "_release": "1dc79b9776",
 ... 
  "_target": "*",
 ...
}