Access token removal fix on hook removal

[mpsonntag]

On hook removal the validation hook access tokens for a repository are now only removed, if there are no more remaining active hooks left. Closes #105.

[coveralls]

Pull Request Test Coverage Report for Build 2760451421

• 33 of 113 (29.2%) changed or added relevant lines in 8 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.1%) to 36.7%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/web/fail.go	3	5	60.0%
internal/web/ginutils.go	0	3	0.0%
internal/web/validate.go	12	20	60.0%
internal/web/results.go	6	21	28.57%
internal/web/hooks.go	2	24	8.33%
internal/web/user.go	4	34	11.76%

Files with Coverage Reduction	New Missed Lines	%
internal/web/user.go	1	16.15%

Totals
Change from base Build 2753139380:	-0.1%
Covered Lines:	694
Relevant Lines:	1891

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💛 - Coveralls