Adds "Chance to Jam" to Sensor Strength tooltip

* Adds a new attribute to fits, `ecmProjectedStr`, which defaults to `1`. This will store the current modified value of the jam strengths applied to the ship
* Utilizes previously unused effect `ewTestEffectJam` to modify `ecmProjectedStr`
* Adds new property to fit, `jamChance`
* Adjusts stats pane to include this info in the Sensor Str. tooltip

I originally wanted to have the jam chance show up next to the sensor strength, like so: 

`Sensor Str.: 14.4 | 30%`. 

However, due to the way stats are organized (seems they need to be a strict `str: int/float`) and cached, I could not achieve this without some major hacking. Something to look more into when time permits.

~~There is also a bug if you project a fit with overloaded ECM onto a target ship. The target ship will show incorrect chance. This is, as far as I'm aware, not due to this feature but an underlying issue that hasn't been determined yet. I will open a new issue for that.~~ Nevermind, I simply did not add a projection check to an effect that needed it. It's been committed to the pull request

Here's a screenshot. The jammer ship is unbonused and has a single overheated White Noise II. Doing that calcs by hand shows that this is the expected value.

![screenshot 2014-08-08 10 50 40](https://cloud.githubusercontent.com/assets/3904767/3858186/61f51628-1f0b-11e4-969a-bef36e969da5.png)