Revert "Support assigning 0 to http/https port for OS assigned port."

This reverts commit e4c63c60c907766d68205e5156d15d9e3318631b.

Conflicts:
	grails-bootstrap/src/main/groovy/org/codehaus/groovy/grails/cli/fork/ForkedGrailsProcess.groovy
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/InlineExplodedTomcatServer.groovy
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/IsolatedTomcat.java
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/IsolatedWarTomcatServer.groovy
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/TomcatKillSwitch.java
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/TomcatServer.groovy
	grails-plugin-tomcat/src/main/groovy/org/grails/plugins/tomcat/fork/ForkedTomcatServer.groovy
	scripts/_GrailsTest.groovy