URL Cleanup (#536)

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://repo.spring.io/libs-milestone-local with 2 occurrences migrated to:
  https://repo.spring.io/libs-milestone-local ([https](https://repo.spring.io/libs-milestone-local) result 302).
* [ ] http://repo.spring.io/libs-snapshot-local with 2 occurrences migrated to:
  https://repo.spring.io/libs-snapshot-local ([https](https://repo.spring.io/libs-snapshot-local) result 302).
* [ ] http://repo.spring.io/release with 1 occurrences migrated to:
  https://repo.spring.io/release ([https](https://repo.spring.io/release) result 302).

# Ignored
These URLs were intentionally ignored.

* http://maven.apache.org/POM/4.0.0 with 12 occurrences
* http://www.w3.org/2001/XMLSchema-instance with 6 occurrences

.settings.xml

@@ -21,7 +21,7 @@
 		<repository>
 			<id>spring-snapshots</id>
 			<name>Spring Snapshots</name>
-			<url>http://repo.spring.io/libs-snapshot-local</url>
+			<url>https://repo.spring.io/libs-snapshot-local</url>
 			<snapshots>
 				<enabled>true</enabled>
 			</snapshots>
@@ -29,7 +29,7 @@
 		<repository>
 			<id>spring-milestones</id>
 			<name>Spring Milestones</name>
-			<url>http://repo.spring.io/libs-milestone-local</url>
+			<url>https://repo.spring.io/libs-milestone-local</url>
 			<snapshots>
 				<enabled>false</enabled>
 			</snapshots>
@@ -37,7 +37,7 @@
 		<repository>
 			<id>spring-releases</id>
 			<name>Spring Releases</name>
-			<url>http://repo.spring.io/release</url>
+			<url>https://repo.spring.io/release</url>
 			<snapshots>
 				<enabled>false</enabled>
 			</snapshots>
@@ -47,7 +47,7 @@
 		<pluginRepository>
 			<id>spring-snapshots</id>
 			<name>Spring Snapshots</name>
-			<url>http://repo.spring.io/libs-snapshot-local</url>
+			<url>https://repo.spring.io/libs-snapshot-local</url>
 			<snapshots>
 				<enabled>true</enabled>
 			</snapshots>
@@ -55,7 +55,7 @@
 		<pluginRepository>
 			<id>spring-milestones</id>
 			<name>Spring Milestones</name>
-			<url>http://repo.spring.io/libs-milestone-local</url>
+			<url>https://repo.spring.io/libs-milestone-local</url>
 			<snapshots>
 				<enabled>false</enabled>
 			</snapshots>