[UIMA-6444] Automatically sign Eclipse plugins during release builds

- Tried this again with Tycho 3 - still no success
- Removed enforcer rule on java version during release - we use the toolchains plugin now, so this is not needed
- Add a comment regarding the execution of gpg via ant and the tycho-gpg-plugin clashing as the file set created by both overlap (but is not equal!) and gpg fails if a file it wants to generate already exists
diff --git a/uimaj-eclipse-update-site/pom.xml b/uimaj-eclipse-update-site/pom.xml
index 4f11189..0f2b7d4 100644
--- a/uimaj-eclipse-update-site/pom.xml
+++ b/uimaj-eclipse-update-site/pom.xml
@@ -92,6 +92,10 @@
                         <exclude name="META-INF/**/*" />
                       </fileset>
                     </checksum>
+                    <!--
+                      This will clash with the tycho-gpg-plugin which also generates ASC files
+                      for some of the artifacts
+                    -->
                     <apply executable="gpg" dir="target/repository" failonerror="true">
                       <arg value="--detach-sign" />
                       <arg value="--armor" />
diff --git a/uimaj-parent/pom.xml b/uimaj-parent/pom.xml
index 6e733bb..4059d1c 100644
--- a/uimaj-parent/pom.xml
+++ b/uimaj-parent/pom.xml
@@ -341,34 +341,6 @@
       <properties>
         <tycho-include-gpg-signatures>true</tycho-include-gpg-signatures>
       </properties>
-      
-      <build>
-        <plugins>
-          <plugin>
-            <groupId>org.apache.maven.plugins</groupId>
-            <artifactId>maven-enforcer-plugin</artifactId>
-            <executions>
-              <execution>
-                <id>enforce-java</id>
-                <goals>
-                  <goal>enforce</goal>
-                </goals>
-                <configuration>
-                  <rules>
-                    <requireJavaVersion>
-                      <!-- 
-                       - Ensure that releases are made with a Java 1.8 since that's our minimum
-                       - version atm.
-                       -->
-                      <version>[1.8,1.9)</version>
-                    </requireJavaVersion>
-                  </rules>
-                </configuration>
-              </execution>
-            </executions>
-          </plugin>
-        </plugins>
-      </build>
     </profile>
 
     <profile>