Added feature to define version specifying regex and version replacement string
Added documentation for regex changes
Merge pull request #1 from pjangam/RegexSupport

Regex support
[maven-release-plugin] prepare release change-assembly-version-plugin-1.4
[maven-release-plugin] prepare for next development iteration
added null check along with empty string check as last commit changes were breaking older jobs
Merge pull request #2 from pjangam/RegexSupport

added null check along with empty string check
[maven-release-plugin] prepare release change-assembly-version-plugin-1.4.1
[maven-release-plugin] prepare for next development iteration