fix(tooltip): remove child scope requirement

tt_ scope variables are now in the ttScope which is specific to each
tooltip directive (multiple tooltip directives can now run on the same
element).

This allows tooltips to be used alongside any directive that may or
may not require different scope types.

Closes #1269
Fixes #2320
Fixes #2203

src/popover/test/popover.spec.js

@@ -2,7 +2,8 @@ describe('popover', function() {
   var elm,
       elmBody,
       scope,
-      elmScope;
+      elmScope,
+      tooltipScope;
 
   // load the popover code
   beforeEach(module('ui.bootstrap.popover'));
@@ -20,10 +21,11 @@ describe('popover', function() {
     scope.$digest();
     elm = elmBody.find('span');
     elmScope = elm.scope();
+    tooltipScope = elmScope.$$childTail;
   }));
 
   it('should not be open initially', inject(function() {
-    expect( elmScope.tt_isOpen ).toBe( false );
+    expect( tooltipScope.isOpen ).toBe( false );
 
     // We can only test *that* the popover-popup element wasn't created as the
     // implementation is templated and replaced.
@@ -32,7 +34,7 @@ describe('popover', function() {
 
   it('should open on click', inject(function() {
     elm.trigger( 'click' );
-    expect( elmScope.tt_isOpen ).toBe( true );
+    expect( tooltipScope.isOpen ).toBe( true );
 
     // We can only test *that* the popover-popup element was created as the
     // implementation is templated and replaced.
@@ -42,7 +44,7 @@ describe('popover', function() {
   it('should close on second click', inject(function() {
     elm.trigger( 'click' );
     elm.trigger( 'click' );
-    expect( elmScope.tt_isOpen ).toBe( false );
+    expect( tooltipScope.isOpen ).toBe( false );
   }));
 
   it('should not unbind event handlers created by other directives - issue 456', inject( function( $compile ) {