fix(module:core,root): ensure compatibility to v4

[trotyl]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: fixes #69

What is the new behavior?

DOCUMENT in @angular/common was introduced in 4.3.0-rc.0, as we documented the compatibility for ~4.0.0, it should not be used in production codes. (Won't matter for showcase or documentation)

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

Need to be revisited after v5 being the minimal requirements.

[coveralls]

Coverage increased (+0.007%) to 33.624% when pulling ba08f77 on trotyl:fix-compat-v4 into 5f11664 on NG-ZORRO:master.

[vthinkxie]

it seems that there existsimport { DOCUMENT } from '@angular/common' in other components and tests, should it be fix in an other pr?