Feeds Management and Subscription

[qjqqyy]

builds on #107

Summary of changes

• add feeds context
• implement basic feeds management (As a regular user, I can subscribe to multiple feeds and list all of them #69)
  • subscribe / sub (imports the feed wholesale into reading list)
  • unsubscribe
  • clear (defer to v1.4 or later)
• updating from feeds (also As a regular user, I can subscribe to multiple feeds and list all of them #69)

Part of epics

• RSS feed integration #25 feed integration

[coveralls]

Pull Request Test Coverage Report for Build 596

• 61 of 168 (36.31%) changed or added relevant lines in 16 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-3.5%) to 84.469%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/seedu/address/storage/StorageManager.java	14	16	87.5%
src/main/java/seedu/address/logic/parser/SubscribeCommandParser.java	0	3	0.0%
src/main/java/seedu/address/MainApp.java	11	15	73.33%
src/main/java/seedu/address/model/UserPrefs.java	5	9	55.56%
src/main/java/seedu/address/logic/parser/RefreshCommandParser.java	0	6	0.0%
src/main/java/seedu/address/logic/parser/UnsubscribeCommandParser.java	0	6	0.0%
src/main/java/seedu/address/logic/parser/EntryBookFeedsParser.java	1	12	8.33%
src/main/java/seedu/address/logic/commands/UnsubscribeCommand.java	0	12	0.0%
src/main/java/seedu/address/model/ModelManager.java	9	23	39.13%
src/main/java/seedu/address/logic/commands/SubscribeCommand.java	0	22	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/main/java/seedu/address/storage/StorageManager.java	1	89.19%

Totals
Change from base Build 583:	-3.5%
Covered Lines:	1996
Relevant Lines:	2363

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💛 - Coveralls

[epicfailname]

lgtm