fix(data-table): block (rowClick) event when clicking on checkbox (closes #611)

[emoralesb05]

even though clicking on the checkbox is still clicking on the row, we need to block this since people want to navigate when clicking on row and select when clicking on checkbox.

#611

What's included?

• block (rowClick) event when click event target is md-pseudo-checkbox
• unit test for this particular use case

Test Steps

• ng serve
• Go to data-table demo http://localhost:4200/#/components/data-table
• Go to last demo and enable clickable
• See that now it only shows the dialog when clicking on the row and not when toggling the checkboxes.

General Tests for Every PR

• ng serve --aot still works.
• npm run lint passes.
• npm test passes and code coverage is not lower.
• npm run build still works.

[jeremysmartt]

Made an update to this. Instead of looking for a tag name (MD-PSEUDO-CHECKBOX) to know to stop the event propogation, I added an attribute to the tag to look for. Looking for the tag name could be problematic in that what if someone wants to put their own md-pseudo-checkbox on a cell and doesn't want the event to be stopped. And in fact anyone could now use this new attribute stopRowClick on any of their own cells if they wanted to stop the event from happening for any number of reasons.

[emoralesb05]

Awesome, its more flexible this way and not dependent of the element.