I2c class now uses more C like constructs for added efficiency when using C++
and no longer returns a binary string when doing read() calls. This change also
removes the use of std::string in the SWIG API for read/write which never
worked very well. This also renames single write/read calls to {write,read}Byte
as whilst overloading works in C++ well it's a little confusing and only works
because {write,read}() calls have 2 arguments which will not be the case in the
SWIG API where those calls take a single argument (bytearray or node::Buffer),
especially in js where functions have no explicit args this does not work well.
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
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