add class to execute pig tasks
add first step of semantic pipeline

jimjh - I don't agree with this change. If luigi doesn't import hive tasks,
hadoop tasks etc inside __init__.py, why should it import pigtask? We should
get rid of this when we can.
add S3 get function to get the content of S3 bucket to local folder
since script_parameters returns a dict, encode it as such
make virtualenv deb for luigi
add S3#get to cp the content of S3 bucket to local
add step before sp pipeline is run which moves files from S3 to hdfs for distributed cache.
adjust format for how to recursively delete a directory on hadoop.  Test on hadoop 1.0.3 on EMR
bumped version to 1.0.17-q2

where 'q2' refers to quixey's changes
no longer needing S3 keys in pig scripts
Run pig with -c flag