🚀 use isolated tmp (resolves #15)

[jsmedmar]

Make sure that tmp dirs are removed, that singularity doesn't overwrite $HOME and that tmp dirs are unique.

• [x] 🐛   Bug fix
• [ ] 🚀   New feature
• [x] 🔧   Code refactor
• [ ] ⚠️   Breaking change that would cause existing functionality to change
• [x] 📘   I have updated the documentation accordingly
• [x] ✅   I have added tests to cover my changes

[codecov[bot]]

Codecov Report

Merging #16 into master will decrease coverage by 0.82%. The diff coverage is 92.85%.

@@            Coverage Diff             @@
##           master      #16      +/-   ##
==========================================
- Coverage     100%   99.17%   -0.83%     
==========================================
  Files           5        5              
  Lines         219      243      +24     
==========================================
+ Hits          219      241      +22     
- Misses          0        2       +2

Impacted Files	Coverage Δ
toil_container/jobs.py	100% <100%> (ø)	:arrow_up:
toil_container/containers.py	98.05% <92.59%> (-1.95%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update e53eba8...1fb5b2b. Read the comment docs.