increase bind performance

Instead of making N calls to getProductById, it makes sense to
make one call to getProductsByIds then loop through the result.

Adds a new method for IT to implement in ProductServiceAdapter. Here is a sample graph. In the graph *byid* represents the old getProductById and *byids* represents the new getProductsByIds method.

http://jmrodri.fedorapeople.org/byid-vs-byids.png

TEST
--------
**master**
* deploy *master* branch
* run the @dgoodwin 's bind performance script:
```
cd buildconf/scripts
./bind-performance.rb
```
* Observe the performance, especially of the 50th and 51st item. It will be about 30+ seconds.

**bindperf**
* deploy *bindperf* branch
* run the @dgoodwin 's bind performance script:
```
cd buildconf/scripts
./bind-performance.rb
```
* Observe the performance, especially of the 50th and 51st item. It will be about 4 - 5 seconds.