DATACMNS- 1500 - 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 switched to an https URL with a 2xx status. While the status was successful, your review is still recommended.

* http://maven.apache.org/xsd/maven-4.0.0.xsd with 1 occurrences migrated to:
  https://maven.apache.org/xsd/maven-4.0.0.xsd ([https](https://maven.apache.org/xsd/maven-4.0.0.xsd) result 200).
* http://repo.spring.io/plugins-release with 1 occurrences migrated to:
  https://repo.spring.io/plugins-release ([https](https://repo.spring.io/plugins-release) result 302).

# Ignored
These URLs were intentionally ignored.

* http://maven.apache.org/POM/4.0.0 with 2 occurrences
* http://www.w3.org/2001/XMLSchema-instance with 1 occurrences

Original pull request: #349.

pom.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
 
 	<modelVersion>4.0.0</modelVersion>
 
@@ -252,7 +252,7 @@
 	<pluginRepositories>
 		<pluginRepository>
 			<id>spring-plugins-release</id>
-			<url>http://repo.spring.io/plugins-release</url>
+			<url>https://repo.spring.io/plugins-release</url>
 		</pluginRepository>
 	</pluginRepositories>