Expose all HAR "entry" fields

[tortila]

Expose all HAR "entry" fields.

Closes #35

Description

Added a new property in the Request class to expose all the information about a single entry that was recorded in the HAR file, and that used to be ignored in our intermediate representation.

Types of Changes

• New feature (non-breaking change which adds functionality)
• Documentation / non-code

Review

Reviewers' checklist:

• If this PR implements new flows or changes existing ones, are there
  good tests for these flows?
  If this PR rather removes flows, are the obsolete tests removed as well?
• Is the documentation still up-to-date and exhaustive? This covers both
  technical (in source files) and functional (under docs/) documentation.
• Is the changelog updated?
• Does the new version number correspond to the actual changes from this PR?
  In doubt, refer to https://semver.org.

[zincr]

🤖 zincr found 0 problems , 0 warnings

✅ Large Commits
✅ Approvals
✅ Specification
✅ Dependency Licensing

[tortila]

This is WIP until the issue of failing Travis build is solved...

[tortila]

Travis build is now back to normal with a simple workaround of downgrading pip. I will follow up in the original issue or create a new one once I know the exact way to reproduce the error. This PR is now ready to be reviewed 😄

[thilp]

Looks good! 🎉