Make javax.servlet-api provided

[kinow]

The javax.servlet-api jar was scoped to compile, and because of this I couldn't run Cantaloupe in Eclipse. When trying to run with mvn clean tomcat:run I got:

Jul 25, 2017 12:52:48 PM org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet /Cantaloupe threw load() exception
java.lang.ClassCastException: edu.illinois.library.cantaloupe.EntryServlet cannot be cast to javax.servlet.Servlet
	at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1116)
	at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:993)
	at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4350)

Marking it as provided, everything works in Eclipse. Running mvn clean package -DskipTests, I get the .war and .zip files.

Comparing the WAR and ZIP files, with the contents of Cantaloupe-3.3.2.zip that I just downloaded, everything looks fine. I cannot find the servlet JAR in there. And in the root of the WAR I can see the javax folder. Same for the WAR file within the ZIP.

Am I missing anything? Is that an OK change? If so, it would be easier for users running mvn tomcat:run (or jetty, winstone, etc) to develop new features and test :-)

Thanks
Bruno

[kinow]

For what's worth, running the tests in develop branch I got:

Tests run: 1341, Failures: 8, Errors: 135, Skipped: 21

Running on the branch of this pull request, I got:

Tests run: 1341, Failures: 6, Errors: 118, Skipped: 21

Less failures and errors, though not really sure why.