macros 1.1

Added
- different setter pattern, e.g. `#[builder(pattern="immutable")]`
- private setters, e.g. `#[builder(private)]`
- additional debug info via env_logger, e.g. `RUST_LOG=derive_builder=trace cargo test`
- prefixes, e.g. `#[builder(setter_prefix="with")]`
- field specific overrides
- customize builder name, e.g. `#[builder(name="MyBuilder")]`

Changed
- migration to macros 1.1
- migration to traditional builder pattern
  i.e. seperate `FooBuilder` struct to build `Foo`
=> please refer to the new docs

Fixed
- missing lifetime support #21

fix #27

preserve ordering of attributes

Have a look at the [Changelog][CHANGELOG.md#020---2016-08-22]

Or: https://github.com/colin-kiegel/rust-derive-builder/compare/v0.1.0...v0.2.0

first implementation

- generate setter methods
- support for generic structs