binman: Support compressed entries

Add support for compressing blob entries. This can help reduce image sizes
for many types of data. It requires that the firmware be able to
decompress the data at run-time.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/.travis.yml b/.travis.yml
index ea3b20e..2b759c9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -27,6 +27,7 @@
     - wget
     - device-tree-compiler
     - lzop
+    - liblz4-tool
 
 before_install:
  - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y