FIX MTU PARSING :D :D :D
dorp dorp dorp
Typefix in client; better MTU fix in option

dhcp_clientv4.ml would not build because of a type error;
copy_dhcp_chaddr needed to be used, instead of get_dhcp_chaddr, as an
argument to the function which generates a human-readable string from
the raw hex.

dhcpv4_option.ml now parses variable-length MTU options correctly,
although it seems that unikernels don't respect this value and will send
unfragmented packets of size greater than the transmitted MTU.
dhcpv4_option.ml: make function get_number for variable-size int reads

Some DHCP options require number parsing for buffers of specified sizes.
Of the DHCP options currently supported, only MTU parsing requires this;
however, future options may require it as well.
dhcpv4_option: fix parsing crash when option max-size is set
dhcp_clientv4.ml and dhcpv4_option.ml: removed debug output
dhcp_clientv4.ml : clean up chaddr printing
dhcp_clientv4.ml : revert unnecessary variable name change
dhcp_clientv4.ml : remove some unnecessary changes
Restore TODO
clarify MTU todo + xref to issue
Bump to 1.1.2 and regenerate with OASIS 0.4.4
Merge pull request #49 from avsm/yomimono-dhcp-option-parsing-fixes

Updates to dhcp option parsing fixes