[server][tools] Don't use "XXX.h" style include

It is for headers in the current directory. server/tools/ doesn't have
any headers. So <XXX.h> style include is reasonable.
Merge pull request #519 from project-hatohol/dont-use-double-quote-include-for-headers-not-in-current-directory

[server][tools] Don't use "XXX.h" style include