#2020 extractExecutableFromJar now makes the target directory if necessa...

...ry

Closes #2020
I'm not, I just moved it [here](https://github.com/getlantern/lantern/pull/2021/files#diff-1e3f2dd15237e82c293f24fa19bf8b09R1275)

The reason I moved it is that we only need to delete the old file if it actually existed.  In the case where the old file didn't exist, we'll call delete unnecessarily and log a spurious warning because delete() returns false.