Feature limit number of scans

[epi052]

closes #80
closes #77

Branching checklist

• There is an issue associated with your PR (bug, feature, etc.. if not, create one)
• Your PR description references the associated issue (i.e. fixes [FEATURE REQUEST] Dynamically tuning concurrency/connection limit or bailing after n connection failures #123)
• Code is in its own branch
• Branch name is related to the PR contents
• PR targets master

Static analysis checks

• All rust files are formatted using cargo fmt
• All clippy checks pass when running cargo clippy --all-targets --all-features -- -D warnings -A clippy::unnecessary_unwrap
• All existing tests pass

Documentation

• New code is documented using doc comments
• Documentation about your PR is included in the README, as needed

Additional Tests

• New code is unit tested
• New code is integration tested, as needed
• New tests pass

[codecov]

Codecov Report

Merging #96 into master will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #96      +/-   ##
==========================================
+ Coverage   93.64%   93.72%   +0.07%     
==========================================
  Files          11       11              
  Lines        1685     1705      +20     
==========================================
+ Hits         1578     1598      +20     
  Misses        107      107              

Impacted Files	Coverage Δ
src/banner.rs	99.63% <100.00%> (+<0.01%)	⬆️
src/config.rs	95.12% <100.00%> (+0.14%)	⬆️
src/parser.rs	100.00% <100.00%> (ø)
src/scanner.rs	91.74% <100.00%> (+0.08%)	⬆️

---

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 6caa6b8...154d8ae. Read the comment docs.