CreateItem fails if Subject contains '&'

[bladerunner2020]

Encountered an error "An error occurred while parsing EntityName.."
Found out that CreateItem fails if Subject contains '&'.

Obviously the reason is that XML are not allowed to contain 5 special characters (&, <, >, ", ').
This could be easily fixed by replacing with &...

Besides Subject there are other places where special characters should be replaced. At least in body text.
I added processing Subject and body text to my code, but I guess would it be better to add to ews-javascript-api?

[gautamsi]

I wanted to keep it minimal dependency on other packages.

escaping internally can have non intended effect. at this time any free form text should be escaped.

[bladerunner2020]

At least, it might be a good idea to add this to documentation. It's not obvious that text should be escaped - everything worked fine in our case for quite a long time till we encountered a subject containing '&'...

[gautamsi]

I will update the docs