Prevent conf values from overwriting command line
More consistent desc usage
More darwin mem stats
Removed unreachable code
Added formatting directives to fmt.Errorf calls

Without the directive the error string generated will contain a
placeholder for the extra values.
Merge pull request #131 from Wessie/unreachable-code

Removed unreachable code
Merge pull request #132 from Wessie/fmt-directive

Added formatting directives to fmt.Errorf calls
Cleaned up the build/build.go script

This is a small cleanup of the file used for building the collector,
the following changes have been made.

1. Only open the main.go file once
2. File AST scanning loop now uses less type-switches, for a single
case these are not worth it.
3. Moved the BasicLit type-assertion outside the cases, this means
we only have to do it once in the code.
4. Cleaned up the writing of the edited file, this now uses a
go/printer.Config with the same options as go/format currently does.
This allows us to write a correctly formatted file straight away.
Merge pull request #134 from Wessie/build-rewrite

Cleaned up the build/build.go script
Switch to using Win32_NetworkAdapter, which is supported in server versions older than 2012
Create lookup table for maping instanceName to InterfaceIndex via Win32_PnPEntity