Stop relying on group split matching to keep separators

"string.path".split(/\./) should return: ["string", ".", "path"]

This is not the case in IE8.
IE returns:  ["string", "path"]

Instead do the split discarding the separators, get model and keypath
from this array. Check unsplit path  to se if the string has a bypass
separator to set the option flag.

This should probably be tested.

@@ -122,11 +122,12 @@ class Rivets.View
           type = attribute.name.replace bindingRegExp, ''
           pipes = (pipe.trim() for pipe in attribute.value.split '|')
           context = (ctx.trim() for ctx in pipes.shift().split '>')
-          path = context.shift().split /(\.|:)/
+          path = context.shift()
+          splitPath = path.split /\.|:/
           options.formatters = pipes
-          model = @models[path.shift()]
-          options.bypass = path.shift() is ':'
-          keypath = path.join()
+          model = @models[splitPath.shift()]
+          options.bypass = path.indexOf(":") != -1
+          keypath = splitPath.join()
 
           if dependencies = context.shift()
             options.dependencies = dependencies.split /\s+/