fix task2 for windows cmd

[thyecust]

This is concerned with #99.

My modification

1. add path.join, otherwise copy function can not properly copy the cc file to the temporary folder
2. replace the single quotation marks with the double quotation marks, otherwise will get The filename, directory name, or volume label syntax is incorrect. on windows cmd.

[thyecust]

Only those with write access to this repository can merge pull requests. @kid-icarus could you help to merge this? Thanks.

[kid-icarus]

@thyecust any way you can test this in a unix environment? we don't currently have automation set up

[pqnet]

The same issue is present on other exercises as well, such as part 3. The root cause is that the copy function doesn't work when "to" is a directory in Windows.