Add support for Bitbucket

[wadackel]

What does this do / why do we need it?

Support for Bitbucket 🎉
Added BitbucketProcessor and options in --init.

How this PR fixes the problem?

• None

What should your reviewer look out for in this PR?

• None

Check lists

• Test passed
• Coding style (indentation, etc)

Additional Comments (if any)

• 🐕 💨

(Refactoring has become necessary ...)

Which issue(s) does this PR fix?

• None

[coveralls]

Pull Request Test Coverage Report for Build 70

• 42 of 104 (40.38%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.9%) to 71.12%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
processor.go	31	33	93.94%
cmd/git-chglog/custom_template_builder.go	1	4	25.0%
cmd/git-chglog/kac_template_builder.go	3	7	42.86%
cmd/git-chglog/config.go	0	53	0.0%

Totals
Change from base Build 67:	-1.9%
Covered Lines:	1352
Relevant Lines:	1901

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💛 - Coveralls