Support new Spring release train versioning and suffixes

[spencergibb]

We are moving to calver with YYYY.MINOR.MICRO suffix for prereleases are -MX, -RCX. For release there is no longer a .RELEASE.

In ProjectVersionTests.should_return_true_for_a_valid_version() the following happens

then(projectVersion("2020.0.0-M1").isValid()).isTrue(); // success
then(projectVersion("2020.0.0-RC2").isValid()).isTrue(); // success
then(projectVersion("2020.0.0").isValid()).isTrue(); // failure

[spencergibb]

Also ProjectVersionTests.should_return_true_for_release_versions() fails for 2020.0.0.

Possible impl for ProjectVersion.isRelease()

	public boolean isRelease() {
		return this.version != null && (
				this.version.contains("RELEASE") ||
						(!isSnapshot() && !isMilestone() && !isRc())
		);
	}

also should_get_major_from_version() fails

[spencergibb]

ProjectVersionTests.should_return_true_for_service_release_versions() fails for 2020.0.1.

pseudo code

if (ends with SR\d || (isRelease() && 3rd component > 0))

[spencergibb]

See also 3658fccdc37fc152236b7980cc3e68fc89837d78

[spencergibb]

ProjectGitHandler.branchFromVersion() can't handle new suffixes 2020.0.0-M1

[marcingrzejszczak]

Added support for branch resolution via https://github.com/spring-cloud/spring-cloud-release-tools/commit/0e3a95f9aa422bfe7863ef17ad131e46b9b9ab42

[spencergibb]

Can this be closed?

[spencergibb]

This is still a problem for at least release notes. It thinks the release train is 2020 when it should be 2020.0