add simple text to recovery UI

- recovery takes a --locale argument, which will be passed by the main
  system

- the locale is saved in cache, in case the --locale argument is
  missing (eg, when recovery is started from fastboot)

- we include images that have prerendered text for many locales

- we split the background states into four (installing update,
  erasing, no command, error) so that appropriate text can be shown.

Change-Id: I731b8108e83d5ccc09a4aacfc1dbf7e86b397aaf
diff --git a/install.h b/install.h
index 1943f02..2ada529 100644
--- a/install.h
+++ b/install.h
@@ -23,7 +23,7 @@
 extern "C" {
 #endif
 
-enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT };
+enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE };
 // Install the package specified by root_path.  If INSTALL_SUCCESS is
 // returned and *wipe_cache is true on exit, caller should wipe the
 // cache partition.