Escape non-ASCII characters in properties files

[olim7t]

Cassandra allows non-ASCII characters in datacenter names, for example DåtåCenter1.

However, the cassandra-rackdc.properties file is decoded using ISO-8859-1, so it needs to use Unicode escapes:

dc=D\u00e5t\u00e5Center1

Currently this is not the case, cass-config-builder writes the unescaped Unicode string:

# Wrong, Cassandra won't decode this properly
dc=DåtåCenter1

Minimal test to reproduce this in build_config_test.clj:

(deftest test-non-ascii-dc
  (let [datacenter-info {:name "DåtåCenter1"}
        definitions-data (test-data/get-definitions-data "cassandra" helper/default-cassandra-version)
        built-configs (bc/build-configs definitions-data {:datacenter-info datacenter-info})]
    (is (= "D\\u00e5t\\u00e5Center1" (get-in built-configs [:cassandra-rackdc-properties :dc])))
  )
)

(This potentially extends to other properties files, I haven't compiled an extensive list.)