Translate teaser headings

Translate the teaser headings on the home page.

Resolves #93 (closed).

src/main/webapp/app/teaserContent/teaserContent.component.html

 
 <div class="row" style="width: 80%;margin-left: auto; margin-right: auto;">
 	<div class="col-sm-3">
-	  <p style="padding-left: 30px;"><strong>Keywords</strong></p>
+	  <p style="padding-left: 30px;"><strong jhiTranslate="teaser.headings.keywords">Keywords</strong></p>
 	  <ul style="list-style-type: circle;">
                 <li *ngFor="let keyWord of keywords"><a (click)="clickKeyword(keyWord.target)"  style="cursor:pointer;">{{keyWord.target}} ({{keyWord.hitCount}})</a></li>
       </ul>
     </div>
 	<div class="col-sm-3">
-	  <p style="padding-left: 30px;"><strong>Programming Languages</strong></p>
+	  <p style="padding-left: 30px;"><strong jhiTranslate="teaser.headings.programmingLanguages">Programming Languages</strong></p>
 	  <ul style="list-style-type: circle;">
                 <li *ngFor="let programmingLanguage of programmingLanguages"><a (click)="clickLanguage(programmingLanguage.target)"  style="cursor:pointer;">{{programmingLanguage.target}} ({{programmingLanguage.hitCount}})</a></li>
       </ul>
     </div>
 	<div class="col-sm-3">
-	  <p style="padding-left: 30px;"><strong>Contributors</strong></p>
+	  <p style="padding-left: 30px;"><strong jhiTranslate="teaser.headings.contributors">Contributors</strong></p>
 	  <ul style="list-style-type: circle;">
                 <li *ngFor="let contributor of contributors"><a (click)="clickContributor(contributor.target)" style="cursor:pointer;">{{contributor.target}} ({{contributor.hitCount}})</a></li>
       </ul>
     </div>
-</div>
\ No newline at end of file
+</div>