Don't show emails by default in CONTRIBUTORS file

scumbag spammers harvest them.

Fixes #5
v0.3.0

 [ENHANCEMENTS]
 - Don't print out the emails in the CONTRIBUTORS file, as it seems spammer
   harvest those. (GH#5)

 [STATISTICS]
 - code churn: 2 files changed, 43 insertions(+), 6 deletions(-)