Multitude of updates

[palfrey]

So, this is basically a vast set of updates. Feel free to tell me to split it out in some way if you'd like to merge it differently.

The big item is "make it work with modern Rust", but there's a bunch of other items in there:

• Update Travis to run against stable/beta/nightly and with(out) Postgres
• Replace time with chrono and rustc-serialize to serde as the former two are deprecated and the latter are active projects
• Add a big "deny" block for a bunch of sensible errors, and fix all of them, especially "Debug for everything"

Thoughts?

[s-panferov]

@palfrey hello! This is the amazing work and I merge it as-is. But I'm little bit ashamed that you've done all this work while the project is not actively maintained by me, because projects like https://github.com/diesel-rs/diesel exist already and I don't feel like I can compete with them. I appreciate your work and I'll publish a version anyway, but I encourage you to try diesel as a properly maintained library.

[palfrey]

Thanks! I'd started looking at Diesel, and then ran into all manner of problems trying to build a testable database connection I could swap in and out with it. This work with Deuterium was part of my efforts towards building a more generic database connection as the SQL work here helped to separate out things, but I ran into later problems trying to work out how to replace placeholders with real values. I've ended up moving beyond it in the end, but figured best to hand back the work so at least if anyone else wanted to pick up things in the future this is there for them.

[s-panferov]

@palfrey awesome, thanks!