Release 0.2.1 - System, Network modules for JVM, bug fixes, maven build

Features

• Support system functions (getArgs, getenv, setenv, system, time, sleep etc.)
• Conversion between Idris list and Java collections
• Support network primitives
• Implement fork with Java Thread
• Fix String to Integer conversion
• Fix switch expression type
• Allow custom Idris 2 boot home directory, integrate idris build into maven