Move "ref_rights" table into Git

Permissions are stored in the project.config file within the
refs/meta/config branch of each project.  This makes the rules
more flexible in the future, as well as adds version control.

For example:

  [access "refs/*"]
    owner = group tools-owners

  [access "refs/heads/*"]
    label-Verified = -1..+1 group tools-dev
    label-Verified = -1..+1 group tools-owners
    label-Code-Review = -2..+2 group tools-owners
    submit = group tools-dev
    submit = group tools-owners

  [access "refs/heads/stable"]
    exclusiveGroupPermissions = read create push
    read = group Anonymous Users
    push = group tools-repo-maintainer

To enable easy remote editing of the configuration rules, the
following access block is added by default to -- All Projects --
and is thus inherited throughout the entire site:

  [access "refs/meta/config"]
    read = group Project Owners
    push = group Project Owners

This configuration section permits any project owner or site
administrator (as they are indirectly always a project owner of
any project) to push changes to the project.config file within
the refs/meta/config branch, updating access (and other project
information) remotely without using the web UI.

Change-Id: Idb56f657a4bf88108ad40bbb19d831e6806b68c5
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/git/VersionedMetaData.java

@@ -69,6 +69,18 @@ public abstract class VersionedMetaData {
     return revision.copy();
   }
 
+  /** Initialize in-memory as though the repository branch doesn't exist. */
+  public void createInMemory() {
+    try {
+      revision = null;
+      onLoad();
+    } catch (IOException err) {
+      throw new RuntimeException("Unexpected IOException", err);
+    } catch (ConfigInvalidException err) {
+      throw new RuntimeException("Unexpected ConfigInvalidException", err);
+    }
+  }
+
   /**
    * Load the current version from the branch.
    * <p>