Fix el-get-async
Hold package lock during "el-get-do-build"
Fix el-get-assoc-regexp
Use el-get-warning-message instead of el-get-display-warning

el-get-display-warning is the primitive and is not meant for direct use.
Don't uninstall ack in test.el

This allows to check the contents of the package directory.
Various restructuring & refactoring
Add el-get-autoloads