Remove unused module tasks.py

Task endpoints have since been implemented under jobs and agents
Merge pull request #151 from guidow/dead_code_removal

Remove unused module tasks.py
removing references to ip column data
removing ip handling in core and agents.py
removing now unused flag and internal config vars for ip address handling in pyfarm-master
removing ip from admin interface
turn off maxDiff length limit
ip -> remote_ip for search
initial conversion from ip -> remote_ip in tests
adding IPv4Address to default_json_encoder
last bit of conversion from ip to remote_ip where needed
readding validate_ip_address which is needed by search
fixing string 'ip'
fixing remote_ip/ip in tests
removing unused global
removing reference to old 'ip'
rename validate_ip_address -> validate_ipv4_address, add validator to ensure at least the format checks out for remote_address
adding minimal invalid ip address validation, updating api_url errors/construction
remove old ip references in agent model tests
removing allowed failure for pymysql, sqlalchemy 0.9.3 has been out for a while