[New] Print the version is going to be installed

[PeterDaveHello]

For user experience enhancement/improvement

before:

$ nvm i 7
######################################################################## 100.0%
Computing checksum with sha256sum
Checksums matched!
Now using node v7.0.0 (npm v3.10.8)

$ nvm i 5
######################################################################## 100.0%
Computing checksum with sha256sum
Checksums matched!
Now using node v5.12.0 (npm v3.8.6)

after:

$ nvm i 7
Start to download and install node v7.0.0
######################################################################## 100.0%
Computing checksum with sha256sum
Checksums matched!
Now using node v7.0.0 (npm v3.10.8)

$ nvm i 5
Start to download and install node v5.12.0
######################################################################## 100.0%
Computing checksum with sha256sum
Checksums matched!
Now using node v5.12.0 (npm v3.8.6)

[PeterDaveHello]

Oops ... @ljharb do you have any suggestion about how to fix this?

[ljharb]

The failing tests check install output - you'll need to add your new nvm_echo line to the expected output.

[ljharb]

The flavor is for internal use - otherwise this will be iojs iojs-v1.0.0 for example. To properly handle flavors, you'd need an if/else, with one message for node, and another for io.js.

[PeterDaveHello]

Okay I'll fix it, thanks.

[PeterDaveHello]

@ljharb thanks for your review, may I have some hints about the output part? Thanks again.

[ljharb]

@PeterDaveHello open the test files in question, look for the "EXPECTED_OUTPUT" variables, and add your new expected output

[PeterDaveHello]

@ljharb thank you so much! After tracing the code you mentions, it became much more clear, maybe we could also improve the expected and got error message to make it much more human readable in future 😄

[PeterDaveHello]

Should be good now, waiting for the CI test!

[ljharb]

if set -e is set, won't this line error out?

I'd prefer a proper if here.

[ljharb]

to avoid errors at referencing unset variables, this needs to be ${NODE_OR_IOJS-} (note the dash)

[ljharb]

Also, while we're making changes, let's have this copy be "Downloading and installing ${NODE_OR_IOJS-} ${VERSION}..." :-)

[PeterDaveHello]

@ljharb all done!