fix(collection): allow { upsert: 1 } for findOneAndUpdate() and update()

This is a very rough edge in the API where findAndModify() treats upsert: 1
as upsert: true, but findOneAndUpdate() and updateX() treat upsert: 1
as upsert: false. CRUD spec does say upsert is a boolean but we've had
upsert: 1 in shell examples for a while so it may be worthwhile to support
both, especially since truthiness is so common in JS.

Port of #1580 to 3.0.0

lib/collection.js

@@ -1014,8 +1014,8 @@ var updateDocuments = function(self, selector, document, options, callback) {
 
   // Execute the operation
   var op = { q: selector, u: document };
-  op.upsert = typeof options.upsert === 'boolean' ? options.upsert : false;
-  op.multi = typeof options.multi === 'boolean' ? options.multi : false;
+  op.upsert = options.upsert !== void 0 ? !!options.upsert : false;
+  op.multi = options.multi !== void 0 ? !!options.multi : false;
 
   if (finalOptions.arrayFilters) {
     op.arrayFilters = finalOptions.arrayFilters;
@@ -2124,9 +2124,8 @@ var findOneAndReplace = function(self, filter, replacement, options, callback) {
   var finalOptions = shallowClone(options);
   finalOptions['fields'] = options.projection;
   finalOptions['update'] = true;
-  finalOptions['new'] =
-    typeof options.returnOriginal === 'boolean' ? !options.returnOriginal : false;
-  finalOptions['upsert'] = typeof options.upsert === 'boolean' ? options.upsert : false;
+  finalOptions['new'] = options.returnOriginal !== void 0 ? !options.returnOriginal : false;
+  finalOptions['upsert'] = options.upsert !== void 0 ? !!options.upsert : false;
 
   // Execute findAndModify
   self.findAndModify(filter, options.sort, replacement, finalOptions, callback);