experimental: set up spark.com project

Should be enough to (1) talk to the Java API and (2) provide
a JSON API for the world.

This is really just experimental. MMT should be integrated directly
w/o JSON if possible to avoid nonsensical serialization.

experimental/uloapi/.gitignore

+.idea
+target
+uloapi.iml

experimental/uloapi/pom.xml

+<project>
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>info.mathhub</groupId>
+    <artifactId>uloapi</artifactId>
+    <version>0.1</version>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <!-- JAR w/ dependencies: https://stackoverflow.com/questions/574594/ -->
+
+        <plugins>
+            <plugin>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <mainClass>info.mathhub.uloapi.Main</mainClass>
+                        </manifest>
+                    </archive>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.sparkjava</groupId>
+            <artifactId>spark-core</artifactId>
+            <version>2.5</version>
+        </dependency>
+    </dependencies>
+</project>
\ No newline at end of file

experimental/uloapi/src/main/java/info/mathhub/uloapi/Main.java

+package info.mathhub.uloapi;
+
+import static spark.Spark.*;
+
+public class Main {
+    public static void main(String[] args) {
+        get("/hello", (req, res) -> "Hello World");
+    }
+}