Fix crash when compiling division by a power of 2 from BPF
Add tests for division expansion
Fix division expansion

Assertion about divisor being non-zero should be wrapped in an array
before it is passed to utils.concat.
Merge pull request #70 from mpeterv/fix-bpf-division-crash

Fix crash when compiling division by a power of 2 from BPF
Merge pull request #71 from mpeterv/fix-division-expansion

Fix division expansion