Introduce Make() which is an alias for Parse() and returns a version as value. New() changed to return a pointer.

Breaking changes:
Change New() to Make() to fix pointer vs value problem.

Closes #14

Uses simple JSON string (un)marshaling under the
hood and Parse() on validating unmarshaled content.

Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)

Closes #12

Closes #11

Breaking changes:
Changed from pointers to value arguments.
If this breaks your code, use latest stable v1 (tag:v1.1.0).
You could also use gopkg.in: go get http://gopkg.in/blang/semver.v1

Closes #10

Closes #9

Closes #8

Closes #7

Resolves #6

Version.Scan -> database/sql.Scanner
Version.Value -> database/sql/driver.Valuer

Closes #4
Closes #5

Minor refactor to hasLeadingZeros

Using string slices instead of bytes.Buffer in Version.String()