Scala compatiblity 2.11

This PR makes spire's core compatible with Scala 2.11. The only significant change was around the fact that spire is using quasiquotes (through macro paradise plugin for Scala 2.10) but they got merged into Scala reflection in Scala 2.11. Also, reflection itself was heavily refactored.

Kudos to @xeno-by and @densh who worked hard on preserving source compatibility. Thanks to their stellar work the migration of spire to Scala 2.11 was a piece of :cake:!

With this PR merged you can run:

```
++ 2.11.0-RC1
core/compile
```

in sbt console and watch it compiling successfully.