Fixed error "MSBUILD : error MSB1008: Only one project can be specified."

Wrapped double quotes around file.path. to fix error below which was
caused by spaces in the path to the file.

[gulp] Starting 'default'...
[gulp] Finished 'default' after 5.44 ms
MSBUILD : error MSB1008: Only one project can be specified.
Switch: Studio

For switch syntax, type "MSBuild /help"
[gulp] Build failed!