ESV Bible support

Hi!

I added support for the ESV Bible translation.

Since you targeted the web services API of the ESV Bible, I first looked there. Unfortunately their XML output is broken for some verses. Thus, I decided to use the RSS feed of the ESV's publisher site. You can find it at http://www.gnpcb.org/esv/share/rss2.0/daily/. It outputs the same daily verse as the web services API.

All tests pass, and the gem installation was successful.

I also changed the test for inserting an ellipsis at the end of a non-proper sentence. It says that it inserts an ellipsis when a dot (.) is missing.  But that is not what the function clean_verse_end in votd/helper/text does. It only inserts the ellipsis if the last character is a letter, a comma or a semicolon. Which is sane to do. When you look e.g. at Romans 8:15, you can see that it ends with a quote, but it is still a self-contained verse. Thus, I changed the test description to indicate that the ellipsis should be inserted if the verse ends with a letter, a comma or a semicolon.

I am looking forward to your response. :-)

Kind regards
Sebastian