I’m saw you got an answer on github but I think this is something worth sharing,
As they move closer to 1.0 Beta, Ionic is moving to declaring the position attributes as classes. Here’s a comment from the commits
Use the classes 'has-header', 'has-subheader', 'has-footer', and
'has-tabs' to modify the positioning of the ion-content relative
to surrounding elements.
Before: `<ion-content has-header="true">`
After: `<ion-content class="has-header">`