Implement CharSequenceReader.ready

[robtimus]

Reader.ready() should return

True if the next read() is guaranteed not to block for input, false otherwise

The default implementation is to return false, and that's what CharSequenceReader inherits. This change overrides ready() to return true if there characters can still be returned.

[coveralls]

Coverage increased (+0.07%) to 89.774% when pulling 4fa7b50 on robtimus:CharSequenceReader.ready into 821ab5f on apache:master.

[robtimus]

I've seen that the Travis build has failed, but that's a test unrelated to this change. I don't know why it fails though.

[garydgregory]

I've restarted the build, that tailer test has failed 'randomly' in the past.

[robtimus]

Thanks, it's green now as it should be.