Fix to include .tgz in path.join

[t-ide]

Types of changes

PR for the issue #28

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

Including extention string in path.join method.

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage remained the same at 76.898% when pulling d61b4f7 on t-ide:master into 06c55f7 on node-red:master.

[coveralls]

Coverage remained the same at 76.898% when pulling d61b4f7 on t-ide:master into 06c55f7 on node-red:master.