Updated angular dependencies to 7.2.14

[vishalhulawale]

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines: https://github.com/HackedByChinese/ng2-idle/blob/master/CONTRIBUTING.md#pr
• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x")

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Other... Please describe: Updated version of Angular dependencies to 7.2.14.

What is the current behavior? ( #119 ) Currently, version of Angular dependencies is 6.0.0.

After running npm install, it gives warning as: npm WARN @ng-idle/core@6.0.0-beta.5 requires a peer of @angular/common@^6.0.0 but none is installed. You must install peer dependencies yourself. npm WARN @ng-idle/core@6.0.0-beta.5 requires a peer of @angular/core@^6.0.0 but none is installed. You must install peer dependencies yourself.

What is the new behavior? The version of Angular dependencies should be 7.x.x. This warnings related to Angular version should disappear.

Does this PR introduce a breaking change? (check one with "x")

[ ] Yes
[x] No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:

[coveralls]

Coverage remained the same at 99.372% when pulling f6c0bd3c3bfd0c0003e1d4959c271ff2e79f7105 on vishalhulawale:master into 6826db22d27cb9ff3e7ad84aa47c8ae63ee49a5d on HackedByChinese:master.