Small tweaks to multitapir server and benchmark client.

This PR doesn't do anything interesting. I was re-familiarizing myself with the multitapir server and benchmark client and made some small tweaks along the way. The tweaks don't affect the behavior of the programs at all, but they clean up the code a bit. For example, I clang-formatted stuff, I changed some strtoul calls to stringstream calls, etc. I also removed some broken rules in store/benchmark/micro/Rules.mk that weren't compiling due to some missing files.