Make userMessage and userErrorMessage consistent.

LogUtil.userErrorMessage changes the contents of its dialog depending
upon the content (and/or length) of the incoming message, and this
behavior seems to work pretty well.

Prior to this commit, LogUtil.userMessage would simply wrap the
incoming message in a JLabel and display it, making long messages
nearly unreadable. This commit just copies userErrorMessage and
displays the results from LogUtil.getMessageComponent.

I also went ahead and took advantage of generics and StringBuilder
within LogUtil.getMessageComponent.
Merge pull request #86 from jon4than/logutil-consistency

Make userMessage and userErrorMessage consistent.