Add support for downloading archives with /+archive/foo.tar.gz

Support all the archive formats supported upstream in JGit, with the
exception of zip.

Change-Id: I8cdec13882117f5b716e54479cff903d8b25a933

pom.xml

diff --git a/pom.xml b/pom.xml
index 17ebc66..c1b4555 100644
--- a/pom.xml
+++ b/pom.xml
@@ -70,6 +70,12 @@
 
       <dependency>
         <groupId>org.eclipse.jgit</groupId>
+        <artifactId>org.eclipse.jgit.archive</artifactId>
+        <version>${jgitVersion}</version>
+      </dependency>
+
+      <dependency>
+        <groupId>org.eclipse.jgit</groupId>
         <artifactId>org.eclipse.jgit.junit</artifactId>
         <version>${jgitVersion}</version>
         <exclusions>