Optional siteUrl to createContext

• Merge pull request #89 from DroopyTersen/dev d424fd7
• removed the unused xhr module 662ae69
• added modern support for not having to pass a siteurl to createContext 33c7b2c
• added top=1 to findItem. closes #79 e27a2c3
• doc tweaks 8368699
• documented the profiles namespace b86454c
• moved in SharePoint utils 7b85aac
• doc tweaks fb9eed4
• added list.checkExists 7b631e0
• added profile tests ffe3ad6
• enabled the copyfile test now that write operations work f570b7f
• added a basic add list item test to play with cookup write requests 46fac68
• turned off code coverage to try and speed up jest be1b306
• updated test of namespace default export 2f909ee
• fixed bug in context where cookie header was getting lost if custom headers were passed c826ca8

v4.1.2...v4.2.0