Fix links

[keanecjy]

PR Overview:

• Update code quality issue
• Fix broken links in readme, index, and aboutus

[codecov-io]

Codecov Report

Merging #300 into master will not change coverage.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##             master     #300   +/-   ##
=========================================
  Coverage     49.38%   49.38%           
  Complexity      766      766           
=========================================
  Files           182      182           
  Lines          3327     3327           
  Branches        348      348           
=========================================
  Hits           1643     1643           
  Misses         1577     1577           
  Partials        107      107           

Impacted Files	Coverage Δ	Complexity Δ
...in/java/seedu/internhunter/model/ModelManager.java	78.00% <ø> (ø)	47.00 <0.00> (ø)
.../model/item/exceptions/DuplicateItemException.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...r/model/item/exceptions/ItemNotFoundException.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)

---

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 50b647d...8663a7a. Read the comment docs.

[seanjyjy]

LGTM