Change loss names for LinearSVC and LinearSVR()

the names are now consistent across methods

In LinearSVC:
   'l1' -> 'hinge'
   'l2' -> 'squared_hinge'
In LinearSVR:
   'l1' -> 'epsilon_insensitive'
   'l2' -> 'squared_epsilon_insensitive'
I'm having a hard parsing the meaning of this... care to insert a comment explaining the structure?