List of potentially useful closed PRs

[kaustavha]

Theres a few prs I'll be closing since I wont be working on them anymore but can be re-opened if someone finds them useful.
#877 Adds arguments to hostinfo checks. It can theoretically allow hostinfos to run arbitrary commands and read arbitrary files. Only properly authenticated uses can use this, but perhaps a whitelist would be prudent.
#860 is a mysql/mariadb check which has parity with the similiar ohai-plugin. Merging #877 first would be prudent since that would allow us to pass db name and auth info to the plugin. This PR could be re-opened by anyone working on integrating waldo or a similiar product with the agent since the agents a lot lighter and faster than ohai plugins
#867 allows one to run all the hostinfos together and offers a minor speed improvement on an already fairly fast system. Concerns were expressed about people abusing this endpoint instead of just using hostinfos they need. This reduces 1 call from a client to ele (just /all instead of /types followed by /host_info) and n calls ele<->agent (1 call per hostinfo, but this is happening within the dc and is quite fast)
#923 basically moves utility functions used by hostinfos into the agent toolkit where most misc utility functions live.