Update selection criteria statement

For code4lib 2014, the proposal selection will combine the top 10
highest scoring proposals with a committee selection process to ensure
diversity, per http://wiki.code4lib.org/index.php/2014_Prepared_Talk_Proposals

Signed-off-by: Dan Scott <dan@coffeecode.net>
Merge pull request #7 from dbs/updated_selection_stmt

Update selection criteria statement