Don't allow port 0 as a listen port

Port 0 is not really a valid port. Using it will most likely dynamically
allocate a port to listen on.

src/NzbDrone.Api/Config/HostConfigModule.cs

@@ -24,7 +24,7 @@ namespace NzbDrone.Api.Config
             UpdateResource = SaveHostConfig;
 
             SharedValidator.RuleFor(c => c.Branch).NotEmpty().WithMessage("Branch name is required, 'master' is the default");
-            SharedValidator.RuleFor(c => c.Port).InclusiveBetween(1, 65535);
+            SharedValidator.RuleFor(c => c.Port).ValidPort();
             
             SharedValidator.RuleFor(c => c.Username).NotEmpty().When(c => c.AuthenticationEnabled);
             SharedValidator.RuleFor(c => c.Password).NotEmpty().When(c => c.AuthenticationEnabled);

src/NzbDrone.Core/Validation/RuleBuilderExtensions.cs

@@ -30,7 +30,7 @@ namespace NzbDrone.Core.Validation
 
         public static IRuleBuilderOptions<T, int> ValidPort<T>(this IRuleBuilder<T, int> ruleBuilder)
         {
-            return ruleBuilder.SetValidator(new InclusiveBetweenValidator(0, 65535));
+            return ruleBuilder.SetValidator(new InclusiveBetweenValidator(1, 65535));
         }
 
         public static IRuleBuilderOptions<T, Language> ValidLanguage<T>(this IRuleBuilder<T, Language> ruleBuilder)