- fix the run_enb_ue_virt_s1 script
  - change the Ki value back to the one used

thanks to Supreeth Herle for reporting.

libxslt1-dev is used at least for asn1 and usrp. It breaks the build when in
check_install_additional_tools().
Move it to to check_install_oai_software()

uhd is not part of ubuntu standard repositories >= 14.04.
Move the removal of uhd in its own space and do not fail if it doesn't exists.