Fixed inconsistency between HasIntField and IntField

[froth]

• Created HasInt64Field function.
• Fixed TestTimeout for http_response_test

Required for all PRs:

• CHANGELOG.md updated (we recommend not updating this until the PR has been approved by a maintainer)
• Sign CLA (if not already signed)

[froth]

Had to increase the timeout in http_response_test as all timeouts <1s are ignored.

	// Set default values
	if h.ResponseTimeout.Duration < time.Second {
		h.ResponseTimeout.Duration = time.Second * 5
	}

[danielnelson]

Thank you

[danielnelson]

closes #2806