Configure "step" attribute of all cordova-input-number used.

[albertinad]

Not all of the cordova-number-entry elements were configured properly according to the plugin API specification. This PR is to update the attribute configuration of cordova-number-entry, mostly for the geolocation widget.
This fix #117

[MSLaguana]

Looks like we'll change from half unit steps to full unit on the orientation plugin, but it's still editable so I think that's fine.

Should we be imposing minimums on altitude? It is possible to be below sea level, such as at the dead sea.

Looks good in general.

[albertinad]

@MSLaguana I follow this documentation to set the min and step.

[TimBarham]

Altitude isn't spec'd as >= 0, is it? (seems negative numbers should be valid)

[TimBarham]

Not needed for this PR, but we should provide a way to specify null for values that support it.

[albertinad]

You're right @TimBarham, the spec doesn't specify anything in particular about the value that they can take, like the others. So, negative numbers seems supported too.
I've created an issue for addressing the update of cordova-plugin-geolocation simulation in order to support null and NaN values according to the spec: #141

Thanks!