fix(stark-core): complementary fixes for feature/bootstrap

[christophercr]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NationalBankBelgium/stark/blob/master/CONTRIBUTING.md#-commit-message-guidelines
• 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
[ ] Other... Please describe:

What is the current behavior?

Travis CI build failing due to module "@angularclass/hmr" not found.

What is the new behavior?

Travis CI build successful.

Does this PR introduce a breaking change?

[ ] Yes
[X] No

[christophercr]

@dsebastien I've fixed the issues you had in your PR (except the greenkeeper file which is already in stark but you need to rebase). So you can merge this in your branch and update your PR to Stark master ;)