Caraya should support UTF encoding for user-defined inputs

[francois-normandin]

This is as a follow-up to issue #131 . Although the above-mentioned issue will be fixed in release 1.2, there is still a gap when the developer uses non-ASCII characters in the Assert label. Caraya should be able to store user input in UTF-compatible format so that report classes would be able to process them as such. Interactive UI would also need to support this feature.