colon sign (:) not excluded from filenames

[picrin]

Colon is not excluded from the list of invalid file names in org.elasticsearch.common.Strings.java in line 683. Mentioned line should read:

public static final ImmutableSet INVALID_FILENAME_CHARS = ImmutableSet.of('', '/', '*', '?', '"', '<', '>', '|', ' ', ',', ':');

This bug causes crash to elasticsearch on Windows with following curl line:
curl "http://localhost:9200/bitcoin:9200" -X POST

Here's the link to the code:
https://github.com/elasticsearch/elasticsearch/blob/master/src/main/java/org/elasticsearch/common/Strings.java#L683

[picrin]

Instead of blacklisting characters, one could validate for whitelisted characters.

[clintongormley]

Agreed - we should whitelist instead.

Related to #6736

[clintongormley]

Closing in favour of #9059