Change the location for the downloaded model about allosaurus

[xinjli]

Oh, I did not realize this issue.
It makes a lot of sense, we will fix it

[steveway]

I second this!
At the moment if you package this using something like Pyinstaller then it will redownload the model every start new because pyinstaller cleans up the temporary directory for that afterwards.
Manually selecting where to download the model to and from where to load it would help here.

[steveway]

@toonday This Pull Request implements some functionality for loading models to a manually selectable location:
#28
This has been integrated in release 1.0.1 of allosaurus.