Change edit command to update command

[Jolonauh]

Previously an integer was provided to specify the target person to be edited. The changes are to use the full name of the target person instead. The full name provided as argument is not required to be case sensitive. The edit command is renamed to update.

Fix #17

[codecov]

Codecov Report

Attention: Patch coverage is 90.41096% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 76.35%. Comparing base (859538a) to head (0151cd2).

Files	Patch %	Lines
...va/seedu/address/logic/commands/UpdateCommand.java	87.23%	1 Missing and 5 partials ⚠️
...eedu/address/logic/parser/UpdateCommandParser.java	93.75%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #34      +/-   ##
============================================
+ Coverage     76.33%   76.35%   +0.02%     
- Complexity      445      448       +3     
============================================
  Files            73       73              
  Lines          1424     1434      +10     
  Branches        140      141       +1     
============================================
+ Hits           1087     1095       +8     
- Misses          305      306       +1     
- Partials         32       33       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[pjanthony2001]

Minor issues, but overall LGTM. The testcases might need to be checked once more, because when the old files got deleted, there is no diff to compare to.

[pjanthony2001]

Also, I think you can safely ignore the CodeCov partial