Add explicit foldable-traversable dependency (#73)

* Add explicit foldable-traversable dependency

Fixes #72

* Fix typo

Author: paf31

bower.json

@@ -14,6 +14,7 @@
   "dependencies": {
     "purescript-const": "^3.0.0",
     "purescript-functors": "^2.0.0",
+    "purescript-foldable-traversable": "^3.4.0",
     "purescript-identity": "^3.0.0",
     "purescript-profunctor": "^3.0.0",
     "purescript-sets": "^3.0.0",