explicit use of std::vector instead of buffer/Buffer

There were several scoped 'using buffer = std::vector<uint8_t>;' in
header files. This consolidates the code base to use
std::vector<uint8_t> instead of buffer or Buffer. This makes the code
easier to read and debug.

Change-Id: I918a0f6ca9b8e4b9d331175dccff45cbf4c8379d
Signed-off-by: Vernon Mauery <vernon.mauery@linux.intel.com>
17 files changed