Improve XML parsing error messages

[TrueWill]

Include the filename in XML parsing errors.

Centralize parsing of XML.

Specify the encoding when reading text files. (See https://stackoverflow.com/questions/6456864/why-does-node-js-fs-readfile-return-a-buffer-instead-of-string)

This addresses the latter part of #37

Previous output when there was an XML parsing error:

[error]  Error: Unexpected close tag
Line: 69
Column: 7
Char: >

1 problem found (1 error, 0 warnings)

---

New output:

[error]  Unable to parse XML file "C:\SourceCode\mulesoft-apis\System APIs\wsflx-system-api\impl\wsflx-system-api\src\main\app\global.xml": Error: Unexpected close tag
Line: 69
Column: 7
Char: >

1 problem found (1 error, 0 warnings)

[TrueWill]

Rebased