Updates installation.rst with Ubuntu 18.04 instructions
Updates installation.rst with Ubuntu 18.04 instructions

Basically the same as Ubuntu 16.04
kivy/buildozer,kivy/buildozer,kivy/buildozer,rnixx/buildozer,inclement/buildozer,inclement/buildozer,kivy/buildozer,rnixx/buildozer,inclement/buildozer,rnixx/buildozer,inclement/buildozer,rnixx/buildozer