Support list/add connections in the CLI

[jgao54]

Dear Airflow Maintainers,

Please accept the following PR that

• Add CLI support for listing/adding connections (I left out deleting/editing connections to keep it simple, but could be added in the future if there's a need for that).

Reminder to contributors:

• You must add an Apache License header to all new files
• Please squash your commits when possible and follow the 7 rules of good Git commits

[landscape-bot]

Code quality remained the same when pulling f6c8a96 on jgao54:support-connection-via-cli into 7da6a94 on airbnb:master.

[landscape-bot]

Code quality remained the same when pulling 80b54b3 on jgao54:support-connection-via-cli into 7da6a94 on airbnb:master.

[bolkedebruin]

Please have a look at #1391 I'm not too happy with this kind of functionality directly inside the cli. Yes, this deviates from earlier, but the cli is getting hard to maintain and replicates functionality.

[coveralls]

Coverage increased (+0.05%) to 67.218% when pulling 80b54b30c4976a61943dfa17a02d2a0429687628 on jgao54:support-connection-via-cli into 7da6a94 on airbnb:master.

[jgao54]

@bolkedebruin cool, all good points and glad to see the API support! I'll make changes accordingly once #1391 is merged.

[jgao54]

Closing for now.

[r39132]

@jgao54 @bolkedebruin No need to close this PR. We can always port it to the API model after the fact.

[coveralls]

Coverage decreased (-0.08%) to 67.086% when pulling 80b54b30c4976a61943dfa17a02d2a0429687628 on jgao54:support-connection-via-cli into 7da6a94 on airbnb:master.

[landscape-bot]

Code quality remained the same when pulling 6e4012b on jgao54:support-connection-via-cli into fcba070 on airbnb:master.

[landscape-bot]

Code quality remained the same when pulling cd2ad30 on jgao54:support-connection-via-cli into fcba070 on airbnb:master.

[landscape-bot]

Code quality remained the same when pulling a29e0fd on jgao54:support-connection-via-cli into fcba070 on airbnb:master.

[coveralls]

Coverage increased (+0.06%) to 67.106% when pulling a29e0fd on jgao54:support-connection-via-cli into fcba070 on airbnb:master.

[bolkedebruin]

@jgao54 @r39132 I'm not particularly against merging it now, just hoping that @jgao54 indeed ports the functionality to the API once it stabilizes a bit more ;-).

[jgao54]

@bolkedebruin most definitely :)