Long-term v1.0 arguments syntax [Fixes #43]

[rdsubhas]

• Fixes Improve sub-command args syntax #43
• Fixes Uncomment tests in examples/package_test.go #66
• Arguments to tasks are now specified as follows:

# old
myke task[a=1,b=2] task[a=3,b=4]

# new
myke task --a=1 --b=2 task --a=3 --b=4