OPENNLP-1299: Use HTTPS instead of HTTP to resolve dependencies (#371)

This fixes a security vulnerability in this project where the `pom.xml`
files were configuring Maven to resolve dependencies over HTTP instead of
HTTPS.

Signed-off-by: Jonathan Leitschuh <Jonathan.Leitschuh@gmail.com>

pom.xml

@@ -47,7 +47,7 @@
 		<repository>
 			<id>apache.snapshots</id>
 			<name>Apache Snapshot Repository</name>
-			<url>http://repository.apache.org/snapshots</url>
+			<url>https://repository.apache.org/snapshots</url>
 			<snapshots>
 				<enabled>true</enabled>
 			</snapshots>