bump jquery dependency up to latest 2.x

[russell-miller]

Having angular-knob's jquery dependency be "~2.0.3" means that a project (like mine) that uses a newer 2.x version of jquery will get the following warning when doing a bower install:

Please note that,
    angular-knob#0.0.3 depends on jquery#~2.0.3 which resolved to jquery#2.0.3
    bootstrap#3.3.6 depends on jquery#1.9.1 - 2 which resolved to jquery#2.2.4
    jquery-knob#1.2.13 depends on jquery#>=1.7.0 which resolved to jquery#3.1.0
Resort to using jquery#2.2.4 which resolved to jquery#2.2.4
Code incompatibilities may occur.

It might be even better to change this to something similar to jquery-knob, like ">=2.0.3".

This is a breaking change (I think..?), because at the very least this means jquery.min.js will reside in a different location upon installation.

[russell-miller]

self bump

[russell-miller]

@yunlzheng can you merge please?