URL Cleanup

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed Success
These URLs were fixed successfully.

* http://www.apache.org/licenses/LICENSE-2.0.txt migrated to:
  https://www.apache.org/licenses/LICENSE-2.0.txt ([https](https://www.apache.org/licenses/LICENSE-2.0.txt) result 200).
* http://projects.spring.io/spring-integration migrated to:
  https://projects.spring.io/spring-integration ([https](https://projects.spring.io/spring-integration) result 301).
* http://repo.spring.io/libs-milestone migrated to:
  https://repo.spring.io/libs-milestone ([https](https://repo.spring.io/libs-milestone) result 302).
* http://repo.spring.io/libs-snapshot migrated to:
  https://repo.spring.io/libs-snapshot ([https](https://repo.spring.io/libs-snapshot) result 302).
* http://repo.spring.io/libs-staging-local migrated to:
  https://repo.spring.io/libs-staging-local ([https](https://repo.spring.io/libs-staging-local) result 302).

# Ignored
These URLs were intentionally ignored.

* http://maven.apache.org/POM/4.0.0
* http://maven.apache.org/xsd/maven-4.0.0.xsd
* http://www.w3.org/2001/XMLSchema-instance

basic/mail/pom.xml

@@ -6,7 +6,7 @@
   <version>5.1.1.BUILD-SNAPSHOT</version>
   <name>Mail (IMAP + POP3) Sample</name>
   <description>Mail (IMAP + POP3) Sample</description>
-  <url>http://projects.spring.io/spring-integration</url>
+  <url>https://projects.spring.io/spring-integration</url>
   <organization>
     <name>SpringIO</name>
     <url>https://spring.io</url>
@@ -14,7 +14,7 @@
   <licenses>
     <license>
       <name>The Apache Software License, Version 2.0</name>
-      <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
+      <url>https://www.apache.org/licenses/LICENSE-2.0.txt</url>
       <distribution>repo</distribution>
     </license>
   </licenses>