Update branding to 2.1.6-servicing (#1994)

Per discussion with our team, we want to make the following changes to versioning during servicing updates:

* The versioning on packages with ship with ASP.NET Core should be consistent
* (No change) on packages with changes in them ship during servicing updates
* Version gaps are okay. For example, this repo is producing a patch for 2.1.6, so packages will be 2.1.6. It did not patch for 2.1.4 or 2.1.3 so those versions will be skipped.

This also includes another minor change: for consistency with the rest of the .NET Core teams, pre-release servicing builds will be 2.1.x-servicing-buildnumber.

Author: natemcmaster

version.props

@@ -1,18 +1,18 @@
 <Project>
   <PropertyGroup>
-    <VersionPrefix>2.1.4</VersionPrefix>
-    <VersionSuffix>rtm</VersionSuffix>
-    <PackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(VersionSuffix)' == 'rtm' ">$(VersionPrefix)</PackageVersion>
-    <PackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(VersionSuffix)' != 'rtm' ">$(VersionPrefix)-$(VersionSuffix)-final</PackageVersion>
+    <VersionPrefix>2.1.6</VersionPrefix>
+    <VersionSuffix>servicing</VersionSuffix>
+    <PackageVersion Condition="'$(IsFinalBuild)' == 'true' AND ('$(VersionSuffix)' == 'servicing' OR '$(VersionSuffix)' == 'rtm') ">$(VersionPrefix)</PackageVersion>
+    <PackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(VersionSuffix)' != 'servicing' AND '$(VersionSuffix)' != 'rtm' ">$(VersionPrefix)-$(VersionSuffix)-final</PackageVersion>
     <BuildNumber Condition="'$(BuildNumber)' == ''">t000</BuildNumber>
     <FeatureBranchVersionPrefix Condition="'$(FeatureBranchVersionPrefix)' == ''">a-</FeatureBranchVersionPrefix>
     <VersionSuffix Condition="'$(VersionSuffix)' != '' And '$(FeatureBranchVersionSuffix)' != ''">$(FeatureBranchVersionPrefix)$(VersionSuffix)-$([System.Text.RegularExpressions.Regex]::Replace('$(FeatureBranchVersionSuffix)', '[^\w-]', '-'))</VersionSuffix>
     <VersionSuffix Condition="'$(VersionSuffix)' != '' And '$(BuildNumber)' != ''">$(VersionSuffix)-$(BuildNumber)</VersionSuffix>
 
     <ExperimentalVersionPrefix>0.4.4</ExperimentalVersionPrefix>
-    <ExperimentalVersionSuffix>rtm</ExperimentalVersionSuffix>
-    <ExperimentalPackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(ExperimentalVersionSuffix)' == 'rtm' ">$(ExperimentalVersionPrefix)</ExperimentalPackageVersion>
-    <ExperimentalPackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(ExperimentalVersionSuffix)' != 'rtm' ">$(ExperimentalVersionPrefix)-$(ExperimentalVersionSuffix)-final</ExperimentalPackageVersion>
+    <ExperimentalVersionSuffix>servicing</ExperimentalVersionSuffix>
+    <ExperimentalPackageVersion Condition="'$(IsFinalBuild)' == 'true' AND ('$(ExperimentalVersionSuffix)' == 'servicing' OR '$(ExperimentalVersionSuffix)' == 'rtm') ">$(ExperimentalVersionPrefix)</ExperimentalPackageVersion>
+    <ExperimentalPackageVersion Condition="'$(IsFinalBuild)' == 'true' AND '$(ExperimentalVersionSuffix)' != 'servicing' AND '$(ExperimentalVersionSuffix)' != 'rtm' ">$(ExperimentalVersionPrefix)-$(ExperimentalVersionSuffix)-final</ExperimentalPackageVersion>
     <ExperimentalVersionSuffix Condition="'$(ExperimentalVersionSuffix)' != '' And '$(BuildNumber)' != ''">$(ExperimentalVersionSuffix)-$(BuildNumber)</ExperimentalVersionSuffix>
   </PropertyGroup>
 </Project>