Bumped version to 0.2

Removed previously commited workaround.

Note: Version should be changed in setup.py and yaql/__init__.py
Modified some builtin functions (attribution, filtering) etc to handle objects and dictionary properly:
Strings are not treated as collections anymore.
Exception is now thrown if an unknown property is attempted to be retrieved for an object.
Filtering with non-boolean predicates is no longer possible
CLI is now called as "yaql" command, not "yaql-cli"
Incremented version to 0.2.1
'as' function impelemented, context data retrieval/saving fixed
Removed old code
Added 'switch' and 'for_each' functions
migrated cli functions
Merge branch 'master' into version-0.3

Conflicts:
	setup.py
	yaql/cli/cli_functions.py
	yaql/functions/builtin.py
Version fixed in CLI prompt