updates to documentation page (#219)
updates to documentation page (#219)

* fix layout on Downloads page

There was a big whitespace gap between "deployment options"
and "Version Releases." Fixed.

* restructured and tweaked content on Download page

* moved the package installation process to the top of the page,
  since that's the important part
* added a statement about browser support
* small English tweaks

jtokar/ovirt-site,rafaelmartins/ovirt-site,jtokar/ovirt-site,rafaelmartins/ovirt-site,jtokar/ovirt-site,rafaelmartins/ovirt-site,thatdocslady/ovirt-site,rafaelmartins/ovirt-site,thatdocslady/ovirt-site,thatdocslady/ovirt-site,thatdocslady/ovirt-site,jtokar/ovirt-site