Feature/stepper enhancements

[emoralesb05]

Description

Stepper enhacements to be more inline with md-tab-group/md-tab and bug fixes.

What's included?

• Removed [td-step-content]template and make step content anything inside of it (except templates for label, summary and actions). This fixes the issue where you couldnt reference an element (e.g. #form) inside the td-step-content template from another template (e.g td-step-actions)
• Support for label template template[td-step-label] as an alternative while keeping the easy API [label] input for normal (simple) use cases in td-step
• Update demo and docs.

Usag

 <td-step #step label="Label" sublabel="Sublabel" [active]="active" [disabled]="disabled" [state]="state" (activated)="activeEvent()" (deactivated)="deactiveEvent()">
          <template td-step-label>
            ... add label content (if not used, falls back to [label] input)
          </template>
          ... add content that will be shown when the step is "active"
          <template td-step-actions>
            <button (click)="step.close()">Close</button>
            ... add button elements for the step content (optional)
          </template>
          <template td-step-summary>
            ... add summary that will be shown when step in is "complete" state (optional)
          </template>
        </td-step>     

Test Steps

• npm i
• ng serve
• Check step demo

Question: Should we rename td-steps to td-step-group?