Implement plain view

This implements a way to access plain blobs by path (similar to the
tree view) instead of by sha1.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/Makefile b/Makefile
index 78aad10..a305894 100644
--- a/Makefile
+++ b/Makefile
@@ -61,6 +61,7 @@
 OBJECTS += ui-diff.o
 OBJECTS += ui-log.o
 OBJECTS += ui-patch.o
+OBJECTS += ui-plain.o
 OBJECTS += ui-refs.o
 OBJECTS += ui-repolist.o
 OBJECTS += ui-shared.o