Initial implementation of an elasticsearch indexer in Go

Closes #1 (closed)

README.md

+# GitLab Elasticsearch Indexer
+
+This project indexes Git repositories into Elasticsearch for GitLab. See the
+[homepage](https://gitlab.com/gitlab-org/es-git-go) for more information.
+
+## Building
+
+This project relies on [ICU](http://site.icu-project.org/) for text encoding;
+ensure the development packages for your platform are installed before running
+`make`:
+
+### Debian / Ubuntu
+
+```
+# apt install libicu-dev
+```
+
+### Mac OSX
+
+```
+$ brew install icu4c
+$ export PKG_CONFIG_PATH="/usr/local/opt/icu4c/lib/pkgconfig:$PKG_CONFIG_PATH"
+```