Consider removing the numba warning

[hugohadfieldwayve]

Is your feature request related to a problem? Please describe.
There are scenarios in which a user would like to use this package in an environment without numba installed. By default quaternion raises a warning when it detects that numba is not present. We can squash these warnings with:

with warnings.catch_warnings():
    import quaternion

but this is annoying for the user and makes people not familiar with this package or numba think that there is something wrong with their installation and less willing to adopt it.

Would you consider changing the default behaviour to not raise the warning at all?

[moble]

Yep, good advice. Sorry it took so long to get around to this. :)

[hugohadfieldwayve]

Thanks for the changes Mike!