StringTemplate doesn't support foreign language attributes

We were having some troubles with attributes that contained foreign characters and I was able to isolate the problem to something within StringTemplate. Here is the failing unit test

```
@Test
public void testForeignLanguageParameterWithST() throws Exception {
ST simpleTemplate = new ST("Hi, $param$!", '$', '$');
simpleTemplate.add("param", "String");
String simpleRendered = simpleTemplate.render();
String simpleExpeceted = "Hi, String!";
assertEquals(simpleExpeceted, simpleRendered);

ST foreignTemplate = new ST("Hi, $タイプ$!", '$', '$');
foreignTemplate.add("タイプ", "Template");
String foreignRendered = foreignTemplate.render();
String foreignExpected = "Hi, Template!";
assertEquals(foreignExpected, foreignRendered);
}
```

At this point this we are fine with having this fixed in a newer version of StringTemplate, but for now we need to document the known character set.