Update materials to replace JIRA with GitHub issues.

Change issue links from JIRA to GitHub issues.

Closes #424.

Author: gregturn

README.adoc

@@ -103,17 +103,17 @@ If you are just starting out with Spring, try one of the https://spring.io/guide
 * If you are upgrading, check out the https://docs.spring.io/spring-data/rest/docs/current/changelog.txt[changelog] for "`new and noteworthy`" features.
 * Ask a question - we monitor https://stackoverflow.com[stackoverflow.com] for questions tagged with https://stackoverflow.com/tags/spring-data[`spring-data-rest`].
 You can also chat with the community on https://gitter.im/spring-projects/spring-data[Gitter].
-* Report bugs with Spring Data REST at https://jira.spring.io/browse/DATAREST[jira.spring.io/browse/DATAREST].
+* Report bugs with Spring Data REST at https://github.com/spring-projects/spring-data-rest/issues.
 
 == Reporting Issues
 
-Spring Data uses JIRA as issue tracking system to record bugs and feature requests. If you want to raise an issue, please follow the recommendations below:
+Spring Data uses GitHub as issue tracking system to record bugs and feature requests. If you want to raise an issue, please follow the recommendations below:
 
 * Before you log a bug, please search the
-https://jira.spring.io/browse/DATAREST[issue tracker] to see if someone has already reported the problem.
-* If the issue doesn’t already exist, https://jira.spring.io/browse/DATAREST[create a new issue].
+https://github.com/spring-projects/spring-data-rest/issues[issue tracker] to see if someone has already reported the problem.
+* If the issue doesn’t already exist, https://github.com/spring-projects/spring-data-rest/issues[create a new issue].
 * Please provide as much information as possible with the issue report, we like to know the version of Spring Data that you are using and JVM version.
-* If you need to paste code, or include a stack trace use JIRA `{code}…{code}` escapes before and after your text.
+* If you need to paste code, or include a stack trace use GitHub's flavor of Markdown and wrap your code with *triple-backquotes*.
 * If possible try to create a test-case or project that replicates the issue. Attach a link to your code or a compressed file containing your code.
 
 == Building from Source

src/main/asciidoc/preface.adoc

@@ -6,8 +6,8 @@
 == Project Metadata
 
 * Version control: https://github.com/spring-projects/spring-data-rest
-* Bugtracker: https://jira.spring.io/browse/DATAREST
-* Project page: https://projects.spring.io/spring-data-rest
-* Release repository: https://repo.spring.io/libs-release
-* Milestone repository: https://repo.spring.io/libs-milestone
-* Snapshot repository: https://repo.spring.io/libs-snapshot
+* Bugtracker: https://github.com/spring-projects/spring-data-rest/issues
+* Project page: https://spring.io/projects/spring-data-rest
+* Release repository: https://repo.spring.io/release
+* Milestone repository: https://repo.spring.io/milestone
+* Snapshot repository: https://repo.spring.io/snapshot