SL4FJ dependency version problem

This is due to `edu.ucar:netcdf` lib which comes from `tika-parsers` dependency.

```
[INFO] +- org.apache.tika:tika-parsers:jar:1.5:compile
[INFO] |  +- edu.ucar:netcdf:jar:4.2-min:compile
[INFO] |  |  \- org.slf4j:slf4j-api:jar:1.5.6:compile
```

We can exclude this library from the generated ZIP artifact.

Closes #41.

src/main/assemblies/plugin.xml

@@ -12,6 +12,7 @@
             <useTransitiveFiltering>true</useTransitiveFiltering>
             <excludes>
                 <exclude>org.elasticsearch:elasticsearch</exclude>
+                <exclude>org.slf4j:slf4j-api</exclude>
             </excludes>
         </dependencySet>
         <dependencySet>
@@ -21,6 +22,9 @@
             <includes>
                 <include>org.apache.tika:tika-parsers</include>
             </includes>
+            <excludes>
+                <exclude>org.slf4j:slf4j-api</exclude>
+            </excludes>
         </dependencySet>
     </dependencySets>
 </assembly>