Add solution files for VC11/VS2012

1)Removed "lib*" from the root .gitignore as this was causing issues adding the lib_json project file

2)Added solution/project files for visual studio 2012. Note that these
differ from the 7.1 solution in the following ways:
   *Disable Edit and continue (doesn't work with SafeSEH)
   *Now links with the dll/debug dll version of the runtime (default in 2012)
   *intermediate files are now written to a separate directory
   *disable assembler output as it was causing builds to fail intermittently