Upgrading to latest version of semver to fix (#1817, #1845, #1851).
Possible breaking changes in regards to the way semvers handles pre-releases.
If a version has a prerelease tags (for example, 1.2.3-alpha.3) then it will only be allowed to satisfy comparator sets if at least one comparator with the same [major, minor, patch] tuple also has a prerelease tag.
For example, the range >1.2.3-alpha.0 would be allowed to match the version 1.2.3-alpha.7, but it would not be satisfied by * or 1.2.3. See [semvers](https://github.com/npm/node-semver#prerelease-tags) additional details.
When users of the programmatic API update the version, they may do so without having to inspect the new contents of the bower.json file to find out the new version.
This is useful in scripts where the tag needs to be pushed programatically; the user can push the new tag explicitly.
Added logic to automatically detect smart Git hosts that allow shallow
cloning. This is done by sending an `ls-remote` request to the server
and then evaluating the returned HTTP header fields. For this, Curl
verbose logging is enabled for the `ls-remote` request, since Curl
verbose logging sends the returned HTTP headers to `stderr`.
If the `stderr` output contains the desired header
Content-Type: application/x-git-upload-pack-advertisement
then the server supports shallow cloning.
This approach uses Git and Curl for the heavy lifting. Instead of
implementing the request to the server using a simple HTTP client, Git
is used, since it takes care of authentication using stored credentials.
The used approach should also work for BitBucket, which only sends the
Content-Type header when a specific user agent is used. Using Git to
make the request enables this behavior.
The function to detect the smart Git host
(`GitRemoteResolver.prototype._supportsShallowCloning`) returns a
promise that is resolved when the server's request is evaluated. The
promise handling required an addition to `GitHubResolver.js` - to always
resolve the promise to `true`, since GitHub supports shallow cloning.
Added test cases to verify the new functionality.
