Merge pull request #2 from espeed/master

Updates Pegdown to 1.4.2, Clojure to 1.6.0; Fixes #1
update OWASP HTML Sanitizer to r223 (closes #3); more idiomatic
fix source uri
throw exception on unknown option
add :strikethrough option
misc cleanup
fixes Wrong number of args (2) passed to: html/merge-policies/fn