Due to bintray returning 502 error, must replace repositories

[acetousk]

dl.bintray.com is returning a 502 error see here

The bintray service has been sunsetted according to their website.

I was getting this error:

> Task :runtime:component:moqui-graphql:compileGroovy FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':runtime:component:moqui-graphql:compileGroovy'.
> Could not resolve all files for configuration ':runtime:component:moqui-graphql:compileClasspath'.
   > Could not resolve org.codehaus.btm:btm:3.0.0-SNAPSHOT.
     Required by:
         project :runtime:component:moqui-graphql > project :framework
      > Could not resolve org.codehaus.btm:btm:3.0.0-SNAPSHOT.
         > Unable to load Maven meta-data from http://dl.bintray.com/andimarek/graphql-java/org/codehaus/btm/btm/3.0.0-SNAPSHOT/maven-metadata.xml.
            > Could not get resource 'http://dl.bintray.com/andimarek/graphql-java/org/codehaus/btm/btm/3.0.0-SNAPSHOT/maven-metadata.xml'.
               > Could not GET 'http://dl.bintray.com/andimarek/graphql-java/org/codehaus/btm/btm/3.0.0-SNAPSHOT/maven-metadata.xml'. Received status code 502 from server: Bad Gateway

This change fixes the dependencies by remove the jcenter() repository, and replacing it with mavenCentral(). mavenCentral() doesn't have com.github.ben-manes:gradle-versions-plugin:0.13.0, but gradlePluginPortal() does, so that's why it was added.