Support single input file

[awdeorio]

Add support for a single input file.

Validation

$ tree crawl/
crawl/
├── 00001.html
├── 00002.html
├── 00003.html
└── MANIFEST.txt

1 directory, 4 files

$ cat crawl/MANIFEST.txt 
00001.html
00002.html
00003.html

$ rm -rf output
madoop \
  -input crawl/MANIFEST.txt \
  -output output \
  -mapper /bin/cat \
  -reducer /bin/cat
cat output/*
INFO: Starting map stage
INFO: Finished map executions: 1
INFO: Starting group stage
INFO: Starting reduce stage
INFO: Finished reduce executions: 3
INFO: Output directory: output
00001.html
00002.html
00003.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files	Coverage Δ
madoop/__main__.py	93.75% <ø> (ø)
madoop/mapreduce.py	96.96% <100.00%> (+0.19%)	⬆️

📢 Thoughts on this report? Let us know!.

[MattyMay]

I added a test to cover skipping subdirectories and fixed a typo. LGTM if my changes LGTY.

[awdeorio]

TIL .gitkeep

[awdeorio]

LGTM thanks for the addition