Added version constraint for MannewHipchatBundle.

I changed the composer dependency version constraint for MannewHipchatBundle, since I've created a version 1.0 for MannewHipchatBundle.

The constraint "~1.0" will match all versions up to 2.0 and none of the exposed functionality in MannewHipchatBundle will change before that.

But in the (hopefully) unlikely event of some bug fixes in MannewHipchatBundle, this constraint will ensure that the latest matching version is used :-)