add about page, improve other pages, add smooth scrolls

oser-app/package-lock.json

oser-app/package.json

oser-app/src/app/app-routing.module.ts

...rc/app/showcase-site/about-page/about-page.component.html

...rc/app/showcase-site/about-page/about-page.component.scss

.../src/app/showcase-site/about-page/about-page.component.ts

...pp/showcase-site/contact-page/contact-page.component.scss

.../app/showcase-site/donate-page/donate-page.component.html

.../app/showcase-site/donate-page/donate-page.component.scss

...rc/app/showcase-site/donate-page/donate-page.component.ts

...pp/showcase-site/landing-page/landing-page.component.html

oser-app/src/app/showcase-site/mock-news.ts

oser-app/src/app/showcase-site/sass/_mixins.scss

oser-app/src/app/showcase-site/showcase-site.component.html

oser-app/src/app/showcase-site/showcase-site.component.ts

oser-app/src/assets/img/aboutus-img1.jpg

oser-app/src/assets/img/groupe-oser-bw.jpg

oser-app/src/assets/img/soiree-lancement.jpg

oser-app/src/sass/_variables.scss

oser-app/src/sass/styles.scss