Mono.Addins from nuget

Signed-off-by: Emmanuel Mathot <emmanuel.mahot@gmail.com>
Merge branch 'master' of github.com:Terradue/DotNetOpenSearch

Signed-off-by: Emmanuel Mathot <emmanuel.mahot@gmail.com>

Conflicts:
	.gitignore
	Terradue.OpenSearch/Terradue.OpenSearch.csproj
	Terradue.OpenSearch/packages.config