Update conf/kvm.conf

hint for configuring network settings for KVM users
Update docs/book/src/installation/host/configuration.rst

Example of kvm.conf and modification of /etc/libvirt/qemu/networks/default.xml for adding a static dhcp entry for assigning an ip address for the virtual machine in libvirt.
Update docs/book/src/installation/guest/saving.rst

added some tips for managing snapshots with virsh/KVM
Update docs/book/src/installation/guest/saving.rst

fixing layout
Update docs/book/src/installation/guest/saving.rst

Making the steps for taking a snapshot clearer.
Update docs/book/src/installation/guest/agent.rst

Added documentation for adding the agent to run on startup on Windows.
Update docs/book/src/installation/guest/creation.rst

Note to KVM users when selecting a hard drive image format.
Merge pull request #72 from hughpearse/development

More details to documentation