Implement SHA-256 abstraction

The Large File Storage extension specified by GitHub [1] uses SHA-256 to
compute the ID of large files stored by the extension. Hence implement a
SHA-256 abstraction similar to the SHA-1 abstraction used by JGit.

[1] https://git-lfs.github.com/

Bug: 470333
Change-Id: I3a95954543c8570d73929e55f4a884b55dbf1b7a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
diff --git a/pom.xml b/pom.xml
index 0dda8cf..0393996 100644
--- a/pom.xml
+++ b/pom.xml
@@ -767,6 +767,7 @@
     <module>org.eclipse.jgit.http.apache</module>
     <module>org.eclipse.jgit.http.server</module>
     <module>org.eclipse.jgit.pgm</module>
+    <module>org.eclipse.jgit.lfs</module>
     <module>org.eclipse.jgit.junit</module>
     <module>org.eclipse.jgit.junit.http</module>
 
@@ -774,6 +775,7 @@
     <module>org.eclipse.jgit.ant.test</module>
     <module>org.eclipse.jgit.http.test</module>
     <module>org.eclipse.jgit.pgm.test</module>
+    <module>org.eclipse.jgit.lfs.test</module>
   </modules>
 
 </project>