Implement FindEmailCommand class

[yooplo]

No description provided.

[yooplo]

closes issue #46

[codecov]

Codecov Report

Attention: Patch coverage is 58.33333% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...edu/address/logic/commands/FindByEmailCommand.java	71.42%	1 Missing and 1 partial ⚠️
.../seedu/address/logic/parser/FindCommandParser.java	33.33%	2 Missing ⚠️
...s/model/person/EmailContainsKeywordsPredicate.java	0.00%	0 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ	Complexity Δ
...du/address/logic/commands/AbstractFindCommand.java	100.00% <ø> (ø)	4.00 <0.00> (ø)
...eedu/address/logic/commands/FindByNameCommand.java	100.00% <ø> (ø)	4.00 <0.00> (ø)
...c/main/java/seedu/address/model/person/Person.java	97.14% <100.00%> (-0.08%)	19.00 <0.00> (ø)
...s/model/person/EmailContainsKeywordsPredicate.java	70.00% <0.00%> (+70.00%)	5.00 <0.00> (+5.00)
...edu/address/logic/commands/FindByEmailCommand.java	71.42% <71.42%> (ø)	3.00 <3.00> (?)
.../seedu/address/logic/parser/FindCommandParser.java	70.58% <33.33%> (-9.42%)	4.00 <0.00> (ø)

[KrashKart]

LGTM! This should enable us to find by email

[KrashKart]

LGTM! Let's merge sort

[KrashKart]

This is sufficient for a general instruction to guide the user

[KrashKart]

Perhaps can keep in view to use this.getPredicate() instead of directly accessing the super.predicate field although it is allowed (or remove the getPredicate() entirely, undecided as of now)