Add attendance command

[samlsm]

Closes #140

[codecov-io]

Codecov Report

Merging #142 into master will decrease coverage by 0.40%.
The diff coverage is 86.08%.

@@             Coverage Diff              @@
##             master     #142      +/-   ##
============================================
- Coverage     79.53%   79.13%   -0.41%     
- Complexity      826      853      +27     
============================================
  Files           127      129       +2     
  Lines          2331     2468     +137     
  Branches        244      267      +23     
============================================
+ Hits           1854     1953      +99     
- Misses          418      443      +25     
- Partials         59       72      +13     

Impacted Files	Coverage Δ	Complexity Δ
...main/java/seedu/address/commons/core/Messages.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...u/address/logic/parser/AddLessonCommandParser.java	95.65% <ø> (-0.19%)	4.00 <0.00> (-1.00)
...ress/logic/parser/AddModuleClassCommandParser.java	88.88% <ø> (-1.12%)	3.00 <0.00> (-1.00)
.../address/logic/parser/AddStudentCommandParser.java	100.00% <ø> (ø)	4.00 <0.00> (-1.00)
...u/address/logic/commands/AddAttendanceCommand.java	80.59% <80.59%> (ø)	15.00 <15.00> (?)
...in/java/seedu/address/logic/parser/ParserUtil.java	93.58% <89.47%> (-1.33%)	22.00 <5.00> (+5.00)	⬇️
...dress/logic/parser/AddAttendanceCommandParser.java	94.73% <94.73%> (ø)	3.00 <3.00> (?)
...ain/java/seedu/address/logic/parser/CliSyntax.java	93.33% <100.00%> (+1.02%)	1.00 <0.00> (ø)
...va/seedu/address/logic/parser/TutorsPetParser.java	100.00% <100.00%> (ø)	28.00 <0.00> (+1.00)
...edu/address/model/attendance/AttendanceRecord.java	100.00% <100.00%> (ø)	11.00 <1.00> (+1.00)
... and 6 more

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[junlong4321]

Overall LGTM

[dextertanyj]

Overall looks good, just needs to include the check for a student not in the class.

[dextertanyj]

LGTM! Just a minor suggestion.