v0.4.0

• [NEW] Added a environment variables sub-page to the process view.
• [NEW] Updated psutil to 2.1.1
• [NEW] Added a system-wide connections table on the network page.
• [FIX] Removed accidentally committed print statement.
• [NEW] Added more tests and made some refactorings as a consequence.
• [NEW] Added Travis CI setup and test coverage.
• [NEW] Added filters to system-wide connections table
• [NEW] Some rather large refactorings in general due to added tests.