rewrite/update of convertkit api libary#1

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wamcvey wants to merge 7 commits intojustinabrahms:masterfrom

choosefi:master

Commits on Jun 20, 2019

Commits on Sep 18, 2019

Added handling of paginated returns. Added find_tag() and CLI for subscriber listing by tag
wamcvey
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Commits on Jan 31, 2020

Added find_sequence() method to pull stats for sequences. Also added lazy loading to pull data from first page of paginated results. Convienience method to instatiate a client from a config
wamcvey
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Commits on Feb 1, 2020

Bump version
wamcvey
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Commits on Feb 11, 2020

Bump to 2.2.0. Added Total subscriber interface
wamcvey
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