Update org.ysb33r.gradle:grolifant version and use io.github.rburgst instead of com.burgstaller

[ajothomas]

Symptom:
Master build doesn't work. We run into the following exception:

 What went wrong:
A problem occurred configuring root project 'samza'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not find grolifant-0.12.jar (org.ysb33r.gradle:grolifant:0.12).
     Searched in the following locations:
         https://jcenter.bintray.com/org/ysb33r/gradle/grolifant/0.12/grolifant-0.12.jar
   > Could not find okhttp-digest-1.10.jar (com.burgstaller:okhttp-digest:1.10).
     Searched in the following locations:
         https://jcenter.bintray.com/com/burgstaller/okhttp-digest/1.10/okhttp-digest-1.10.jar

Cause:

• okhttp-digest's group has been changed from com.burgstaller to io.github.rburgst
• org.ysb33r.gradle:grolifant v0.12 isn't available anymore on jcenter. This version gets transitively pulled in today.

Changes:

• Override okhttp-digest's group from com.burgstaller to io.github.rburgst
• Pull in org.ysb33r.gradle:grolifant 0.12.1 instead

Tests:

• ./gradlew build

API Changes:
None

Upgrade Instructions:
None

Usage Instructions:
None