1) Fixing a bug in the constructor of the provided ExcelFile type that allows you to pass a file name.
2) Added a headerrow configuration parameter to the ExcelFile type provider. This allows you use an arbitrary row to generate the properties of the provided row type
3) Extracted some common logic in the ExcelProvider.fs file into functions
Merge branch 'master' of https://github.com/fsharp/fsharpx
Merge pull request #222 from JohnDoeKyrgyz/master

Fixes and enhancements to the Excel type provider