Added linode plugin

plugins/inventory/linode.ini

+# Ansible Linode external inventory script settings
+#
+
+[linode]
+
+# API calls to Linode are slow. For this reason, we cache the results of an API
+# call. Set this to the path you want cache files to be written to. Two files
+# will be written to this directory:
+#   - ansible-Linode.cache
+#   - ansible-Linode.index
+cache_path = /tmp
+
+# The number of seconds a cache file is considered valid. After this many
+# seconds, a new API call will be made, and the cache file will be updated.
+cache_max_age = 300