Added binary search for Collections (fixed)

Added `search` method to collection prototype. automatically used by
`where` and `findWhere` when it is possible to do so.

For `toFind`, the user may provide:
- a comparison function which compares takes one value and returns 1 if the sought value has higher index, -1 if its lower and 0 if the value matches (`comparator` unused)
- a value to search for (the value of the `model[comparator]` sought - requires `comparator` to be a string)
- a model to search for (where `comparator` is a function)

Users may also request that it is the index of the model that is
returned or that the model of highest/lowest index which matches the
comparison is sought.

When no match is found, `undefined` is returned, or if `returnIndex` is true then `-1` is returned instead.

One point that may need to be considered is that the behaviour when a
model is input as `toFind` but the `comparator` is a string is different
from that when `comparator` is a function.