Eliminate Buildscript by publishing to gradlePluginPortal

[codeconsole]

if grails-gradle-plugin is published to gradlePluginPortal,

buildSrc/build.gradle
settings.gradle
and a buildscript { }

are no longer needed for Grails Apps.

Also remove need for

apply plugin:"org.grails.grails-web"
apply plugin:"org.grails.grails-gsp"

grails-gradle-plugin currently consists of

org.grails.grails-core
org.grails.grails-doc
org.grails.grails-gsp
org.grails.grails-plugin
org.grails.grails-profile
org.grails.grails-web extends org.grails.grails-plugin
org.grails.internal.grails-plugin-publish
org.grails.internal.grails-profile-publish

org.grails.grails-web should automatically be applied if org.grails:grails-web-url-mappings is present
org.grails.grails-gsp should automatically be applied if org.grails:grails-gsp is present

[davydotcom]

I suggest moving the contents of grails-web into the grails-core gradle plugin and simplifying some of the structure. A lot of plugins were split instead of just using config to enable/disable available tasks a plugin provides

[codeconsole]

@davydotcom sure, it makes sense to merge grails-web and grails-core. Perhaps grails-gsp should remain separate and we start just by publishing grails-gsp and grails-core plugins?

The hope is in the future I will get around to making grails-gsp independent of grails

[codeconsole]

@davydotcom isn't a simple solution to just merge grails-web into grails-gradle-plugin then make org.grails.grails-plugin and org.grails.grails-gsp subprojects and just publish them? Later the other plugins could be make subprojects as well with a common core if needed

[codeconsole]

actually, we can just publish grails-gradle-plugin and move org.grails.grails-gsp into the grails-gsp project

[jamesfredley]

somewhat related to #351

[matrei]

Related: #54

[jdaugherty]

Somewhat related to #350