forgot Iesi.Collections dependency in nuspec

Author: chester89

src/FluentNHibernate.nuspec

@@ -9,6 +9,7 @@
     <projectUrl>https://github.com/jagregory/fluent-nhibernate/</projectUrl>
 	<dependencies>
 		<dependency id="NHibernate" version="[3.3.1.4000,)" />
+		<dependency id="Iesi.Collections" version="[3.2.0.4000,)" />
 	</dependencies>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>Fluent, XML-less, compile safe, automated, convention-based mappings for NHibernate.</description>