[sailfish] Fixed overlapping of Label with Bubble

The width was 3*Theme.paddingMedium (or 2*Theme.paddingMedium without
an icon) to big.  Correct calculation:

width: parent.width - anchors.margins
  - (icon.visible ? (icon.width + icon.anchors.margins) : 0)
  - bubble.width - bubble.anchors.margins
  - Theme.paddingMedium

Details:
• anchors.margins
  Padding to anchors.left of Label

• icon.anchors.margins
  Padding between Icon and ListItem

• bubble.anchors.margins
  Padding between Bubble and ListItem

• Theme.paddingMedium
  Padding between Label and Bubble

This commit simplifies the code.
[sailfish] Fixed typo

Is  everywhere else.
[sailfish] Bugfix: Feeds.qml lost category after adding a new feed

Closes #114 (on sailfish)