Upgrade Angular to 7+ version.

Main changes:

Upgrade Angular dependencies from ^6.1.0 to ^7.2.6
Upgrade ng-bootstrap from ^3.3.0 to ^4.0.4
Upgrade bootstrap from ^4.1.3 to >=4.3.1
Upgrade core-jg from ^2.5.4 to ^2.6.5
Add hammerjs ^2.0.8 dependency
Upgrade rxjs from ~6.2.0 to ~6.4.0
Upgrade rxjs-compat from ^6.3.3 to ^6.4.0
Upgrade zone.js from ~0.8.26 to ~0.8.29
Remove @angular/cli
Upgrade @angular/compiler-cli and @angular/language-service from ^6.1.0 to ^7.2.6
Upgrade typescript from ~2.9.2 to ~3.1.1