Properly handle the pre-release versions in VersionRange

[keshav-space]

The current univers VersionRange includes the pre-release versions. While this behavior is desirable when dealing with version ranges in a security advisory, it is not appropriate for the version range present in package manifests.

Scenario:

Consider the following release versions for an npm package:
1.0.0, 1.2.0, 2.0.0-rc.1, 2.0.0, 2.1.0, and 3.0.0

Desired Behavior:

• When dealing with version ranges in a security advisory:
  2.0.0-rc.1 in vers:npm/>=1.2.0|<2.0.0 => True

• When dealing with version ranges in manifest files:
  2.0.0-rc.1 in vers:npm/>=1.2.0|<2.0.0 => False

[pombredanne]

Merging duplicate:

• Detect if a version is a prerelease, beta, rc and similar #139

It would be useful to detect if a version is a prerelease, beta, rc and similar. This can then be used when doing version tests to exclude some prerelease optionally