Allow the use of / as a key separator, as described in the sysctl man page

[vasell86]

In RHEL, the sysctl man page describes the use of / as a key separator instead of .:

Debug: Executing: '/usr/sbin/sysctl -n net.ipv4.conf.bond0/1018.rp_filter'
Debug: Executing: '/usr/sbin/sysctl -n net.ipv4.conf.bond0/1018.rp_filter'
Notice: /Stage[main]/Sysctl::Base/Sysctl[net.ipv4.conf.bond0/1018.rp_filter]/value: changed configuration value from '' to '0'
Debug: Executing: '/usr/sbin/sysctl -w net.ipv4.conf.bond0/1018.rp_filter=0'
Debug: Puppet::Type::Sysctl::ProviderAugeas: Save failure details:
/augeas/files/etc/sysctl.conf/error/path = /files/etc/sysctl.conf/files/etc/sysctl.conf/net.ipv4.conf.bond0
/augeas/files/etc/sysctl.conf/error/lens = /opt/puppetlabs/puppet/share/augeas/lenses/dist/sysctl.aug:44.7-46.43:
/augeas/files/etc/sysctl.conf/error/message = Failed to match tree under /files/etc/sysctl.conf/net.ipv4.conf.bond0

 { "1018.rp_filter" = "0" }

with pattern

()
( | { })
t
( | { /#comment/ = /[^\t\n\r ].*[^\t\n\r ]|[^\t\n\r ]/ })

Error: /Stage[main]/Sysctl::Base/Sysctl[net.ipv4.conf.bond0/1018.rp_filter]: Could not evaluate: Failed to save Augeas tree to file. See debug logs for details.

Similar case on this mod: voxpupuli/puppet-augeasproviders_sysctl#17