Exclude pig dependencies from jar

When Pig is included in the lipstick-console jar tomcat won't load the jar causing an error:
```
Caused by: org.hibernate.MappingException: Unable to load class [ com.netflix.lipstick.model.P2jCounters] declared in Hibernate configuration <mapping/> entry
        at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:2369)
        at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:2310)
        at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2290)
        at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2243)
        at org.hibernate.cfg.Configuration.configure(Configuration.java:2194)
        at org.springframework.orm.hibernate3.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:642)
        at org.springframework.orm.hibernate3.AbstractSessionFactoryBean.afterPropertiesSet(AbstractSessionFactoryBean.java:188)
        at org.codehaus.groovy.grails.orm.hibernate.ConfigurableLocalSessionFactoryBean.afterPropertiesSet(ConfigurableLocalSessionFactoryBean.java:176)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1514)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1452)
        ... 61 more
Caused by: java.lang.ClassNotFoundException: com.netflix.lipstick.model.P2jCounters
        at java.lang.Class.forName(Class.java:188)
```
Which is a result of Tomcat rejecting the jar because the Servlet class gets included.