chore: upgrade socket.io to `1.7.1`
chore: upgrade socket.io to `1.7.1`

This contains the fix for the Uint8Array regression in IE9.

Fixes #2190 
johnjbarton/karma,pedrotcaraujo/karma,maksimr/karma,karma-runner/karma,david-garcia-nete/karma,johnjbarton/karma,maksimr/karma,maksimr/karma,pedrotcaraujo/karma,karma-runner/karma,johnjbarton/karma,johnjbarton/karma,pedrotcaraujo/karma,david-garcia-nete/karma,karma-runner/karma,david-garcia-nete/karma,pedrotcaraujo/karma,karma-runner/karma