GUACAMOLE-2139: Add automatic retrieval of license information where absent. Remove unused license info.

doc/licenses/lodash/LICENSE

@@ -2,8 +2,9 @@
 # URL:     https://lodash.com/
 # From:    'OpenJS Foundation' (https://openjsf.org/)
 # License: MIT
+# Source:  https://raw.githubusercontent.com/lodash/lodash/${VERSION}-npm/LICENSE
 #
-# --- BEGIN LICENSE FILE ---
+# --- BEGIN LICENSE FILE [4.17.21] ---
 Copyright OpenJS Foundation and other contributors <https://openjsf.org/>
 
 Based on Underscore.js, copyright Jeremy Ashkenas,
@@ -51,4 +52,4 @@ Files located in the node_modules and vendor directories are externally
 maintained libraries used by this software which have their own
 licenses; we recommend you read them, as their terms may differ from the
 terms above.
-# --- END LICENSE FILE ---
+# --- END LICENSE FILE [4.17.21] ---