Cannot set `pageLoadOptions` in capabilities

[Aaron Shim]

No matter the value provided in cap, it gets overwritten here:

fantoccini/src/session.rs

Line 627 in 97b0d5f

 cap.insert("pageLoadStrategy".to_string(), Json::from("normal")); 

Should it first check to see that it is not overwriting this value before resetting it? According to the Selenium documentation, normal, eager, and none are all valid values.

[Jon Gjengset]

Yep, good catch. Thanks for the PR!

[Jon Gjengset]

Fixed now that #178 has been merged.