fix: add test data to IPFS before fetching it

[achingbrain]

See #806 (comment) for context.

[achingbrain]

Hmm, our tests really shouldn't be going to the network, so unreliable:

  1) .util .urlAdd http:
     Uncaught AssertionError: expected [Error: connect ETIMEDOUT 93.184.216.34:80] to not exist
      at ClientRequest.ipfs.util.addFromURL (test\util.spec.js:120:28)
      at Socket.socketErrorListener (_http_client.js:382:9)
      at emitErrorNT (internal/streams/destroy.js:82:8)
      at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)
      at process._tickCallback (internal/process/next_tick.js:63:19)

  2) .util .urlAdd https:
     Uncaught AssertionError: expected [Error: connect ETIMEDOUT 93.184.216.34:443] to not exist
      at ClientRequest.ipfs.util.addFromURL (test\util.spec.js:130:28)
      at TLSSocket.socketErrorListener (_http_client.js:382:9)
      at emitErrorNT (internal/streams/destroy.js:82:8)
      at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)
      at process._tickCallback (internal/process/next_tick.js:63:19)

[alanshaw]

Agree - #803

[alanshaw]

Merging this anyway - test failures are because of reliance on external services. Issue tracked here #803.