message: cmake: fix bug in STRING REPLACE
  The last argument of STRING REPLACE, which is a variable, has to be
  inside double quotes otherwise it may be misinterpreted.
diff: @@ -69,7 +69,7 @@ execute_process(
  OUTPUT_STRIP_TRAILING_WHITESPACE
  )
  -STRING(REGEX REPLACE v\([0-9]+.[0-9]+.[0-9]+.*$\) \\1 VERSION_STR ${VERSION_STR})
  +STRING(REGEX REPLACE v\([0-9]+.[0-9]+.[0-9]+.*$\) \\1 VERSION_STR "${VERSION_STR}")
  message(STATUS "Version: ${VERSION_STR}")
  add_definitions(-DDRONECODE_SDK_VERSION="${VERSION_STR}")
  