Remove VERSION file

When building in standalone mode, the version specified in the VERSION
file is used as the plugin version.

This makes it difficult to know exactly what version is running.

Remove the version so that the version is generated based on the git
describe.

Change-Id: I2bbf46e37d66a371af3e4fa636c81e092eb150a1
diff --git a/VERSION b/VERSION
deleted file mode 100644
index 9fe2542..0000000
--- a/VERSION
+++ /dev/null
@@ -1,4 +0,0 @@
-# Used by BUCK to include "Implementation-Version" in plugin Manifest.
-# If this file doesn't exist the output of 'git describe' is used
-# instead.
-PLUGIN_VERSION = '2.10'