Move functionality for getting system info to helpers

Common artributes' generator for agents.

Common artributes' generator for agents.

Merge pull request reportportal#90 from iivanou/release_5_0_3

Release version 5.0.3

Add support for the item update call

Merge pull request reportportal#73 from iivanou/syntax_error

Fix syntax issue for Python 2.7

Merge pull request reportportal#71 from iivanou/nested_steps

Add support for nested steps

Merge pull request reportportal#70 from iivanou/rp5_initial

Initial commit for RP v5 client

Merge pull request reportportal#55 from Almost1990/update_version

Update version to trigger upload of the correct release to PyPi

Merge pull request reportportal#47 from reportportal/filland-patch-1

Update setup.py