This is trivial change so I commit this on my discretion.

This is a result of the review.

Comparing the error_code directly causes test issues on some OSes.
See asio_wrapper.h for the details.

- Removed unncessary public:
- Added function description

# Conflicts:
#	src/lib/testutils/io_utils.cc
#	src/lib/testutils/io_utils.h

    Merges in branch 'trac5046'

Fixed couple word nits

src/bin/dhcp4/tests/parser_unittest.cc
    void testFile(const std::string& fname) - removed call to
    unlink as it a: doesn't compile on my Mac and b: is not necessary

 - The parsers converted to SimpleParser
 - Unit-tests updated, cleaned up and corrected
 - Updated examples to actually use the information
 - Updated User's Guide that the empty mac-sources is not allowed

Added memfile without persistence to set_config unit tests. This eliminates
the tests attempting to create the csv file.

Updated copyrights.

Fixed misspelling.