Install dib from pip

diskimage-builder makes releases to PyPI and is not part of the
integrated release. Since it's not, we don't need to consume its
master branch - rather, we can consume its releases.

Change-Id: If9297a28604612140c39dfe44e77107d1372f0bb
diff --git a/lib/dib b/lib/dib
index 3a1167f..d39d801 100644
--- a/lib/dib
+++ b/lib/dib
@@ -32,10 +32,7 @@
 
 # install_dib() - Collect source and prepare
 function install_dib {
-    git_clone $DIB_REPO $DIB_DIR $DIB_BRANCH
-    pushd $DIB_DIR
-    pip_install ./
-    popd
+    pip_install diskimage-builder
 
     git_clone $TIE_REPO $TIE_DIR $TIE_BRANCH
     git_clone $OCC_REPO $OCC_DIR $OCC_BRANCH