add .gitattributes

helps #325

Author: cdunn2001

.gitattributes

@@ -1,6 +1,11 @@
 *           text=auto
+*.h         text
+*.cpp       text
+*.json      text
+*.in        text
 *.sh        eol=lf
 *.bat       eol=crlf
 *.vcproj    eol=crlf
 *.vcxproj   eol=crlf
 *.sln       eol=crlf
+devtools/agent_vm* eol=crlf