Fix confusing licences in several files

During an email conversation on weld-dev, several files were identified to have weird licences. Weld is ASL2 as the project states and these are most likely a forgotten leftovers.
We should edit them to eliminate confusion.

The files are:

• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/bootstrap/api/Singleton.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/bootstrap/api/SingletonProvider.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/bootstrap/api/helpers/IsolatedStaticSingletonProvider.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/bootstrap/api/helpers/TCCLSingletonProvider.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/contexts/AbstractConversationContext.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/contexts/AbstractSharedContext.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/contexts/unbound/DependentContextImpl.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/module/web/context/http/HttpRequestContextImpl.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/module/web/servlet/WeldInitialListener.java
• weld-servlet-shaded-3.1.1.Final-sources.jar/org/jboss/weld/module/web/servlet/WeldTerminalListener.java