Fix clasp logout

[campionfellin]

It now removes .clasprc.json file in the users current directory

Signed-off-by: campionfellin campionfellin@gmail.com

Fixes #124

• npm run test succeeds.
• npm run lint succeeds.
• Appropriate changes to README are included in PR.

[coveralls]

Pull Request Test Coverage Report for Build 153

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 187 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.06%) to 14.089%

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Files with Coverage Reduction	New Missed Lines	%
tests/test.js	16	33.18%
src/utils.js	27	18.64%
index.js	144	6.6%

Totals
Change from base Build 152:	0.06%
Covered Lines:	159
Relevant Lines:	858

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💛 - Coveralls