feature(plugin): Introduce "Clean Branches" plugin, currently as a workaround for a bug in the vcs.go code. 

feature(project): When running project scripts, support the logging of all output within the artifacts, and echo stderr to the console when a script fails 

feature(metrics): Wrap calls to plugin functions with the Sentry/Raven `CapturePanic` wrapper to report plugin errors 

chore(documentation): Improve documentation, introduce an index-generator template (currently unused) based on Material Design. 

feature(plugin): Initial commit of the index-generator plugin; It doesn't generate indexes just yet but does put cool badges in the artifacts directory for use in your markdown files!

Be clever with the destination parent: Split the destination into a slice, pop the last item off the end, and reassemble the path string. 

Better handling of artifact paths to support branch names with slashes (will be nested as subdirectories) 

Support for building branches with more than 3 segments in the ref (such as git-flow style bug/feature branches) 

Debug level logging when  pulling changes (local merging / fast forwarding) for better troubleshooting 

Projects will now continue to build when a one or more branches fail, giving each branch it's own chance to build. 

Plugin: All-Branches: Don't build all branches unless the project has been configured as such (one branch defined as wildcard in the config)

Plugins: Introduce the `all-branches` plugin, which brings crude wildcard support for building all remote branches. 

Also, move each plugin into it's own dir to prevent package collisions and update makefile accordingly. 

* feature/plugin-support:
  Plugin interface uses memory pointers, so that plugins can directly manipulate variables being used in the program. 
  Getting closer to a usable plugin interface, there are now variables passed to the plugin "hooks" 
  Docker: Build default plugins along with the main binary, before packing 
  Makefile: Build plugins with `make build-plugins`, don't auto-rebuild everything
  Better public/private-ness of types and variables, better plugin example, first actually-working basic plugin interface. 
  Makefile support for creating non-stripped builds with full debug support.
  Make all types and structs public 
  Robustness and logging in the extension/plugin loader  
  Update Makefile to build from `src` directory 
  Modularise code and move into src subdirectory 
  Ignore `.idea` directory (when using IntelliJ / GoLand or similar) 
  Update plugin example and document plugin configuration 
  Begin work on modularisation, documentation, and plugin support

Plugin interface uses memory pointers, so that plugins can directly manipulate variables being used in the program. 

Better public/private-ness of types and variables, better plugin example, first actually-working basic plugin interface. 

(NB: Should be compatible with dlv when run under go 1.9, however due to https://github.com/golang/go/issues/23733 go 1.10 and 1.11 will cause dlv to produce an error)