Added Travis CI jobs to publish installers

[thegecko]

Signed-off-by: thegecko rob.moran@arm.com

This PR introduces electron builds and publishing from TravisCI for the master branch.

I've already created a test publish of the installers here: https://github.com/theia-ide/theia-apps/releases/tag/v0.1.0

Note: These installer binaries are untested and currently unsigned. I will create a separate PR later to introduce signing for macOS and Windows.

Changes

• Added Travis CI jobs to build installers for macOS/Windows/Linux in addition to existing docker jobs which only run on master
• Updated theia-electron project to use latest theia by default to be more stable for users
• Updated git repository URLs in theia-electron project to point at this repo (as it's used by electron-builder for publishing)
• Automatic publishing of installers to GitHub when a draft release exists matching the current version
• Addition of an entry to the wiki which outlines how to publish a release

Decisions to confirm

• theia tag to use for a release (currently this uses what is set in the package.json file which is latest and not next nor an explicit version)
• publishing is done on GitHub (should it be elsewhere?)
• publishing is to the theia-apps repo and not eclipse-theia
• do we need to consider different release channels in future?

Notes:

• Merging this PR should automatically add binaries to a release that has been drafted for v1.2.0.
• There is a build error for theia-next builds on master which I believe is unrelated to these changes

cc @akosyakov @marcdumais-work

[thegecko]

Confirmed the build error is due to https://github.com/eclipse-theia/theia/issues/7974

[akosyakov]

I've tried pre-release for Mac and it did not work for me:

[kittaakos]

I've tried pre-release for Mac and it did not work for me:

The app isn't signed; it's expected, unfortunately.

[akosyakov]

The app isn't signed; it's expected, unfortunately.

The second error is not about singing. It does not start to me if I even override it.

[kittaakos]

The second error is not about singing.

I know; we have this error in the electron app since we ship with the VS Code extension support. It happens every time when the app start has failed. It is this: https://github.com/eclipse-theia/theia/issues/7113

[kittaakos]

It does not start to me if I even override it.

I do not understand this part, can you explain what do you many by even override it?

[thegecko]

Travis CI job is now passing, this should be ready for review.

[marcdumais-work]

The second error is not about singing. It does not start to me if I even override it.

My interpretation: there is a way to bypass the check for signing, but the packaged app still does not work correctly

[marcdumais-work]

I think we'll need to update the README to really spell-out what this application is - an example desktop Theia application. I'll suggest some updates to the package.json as well for the same reason.

[marcdumais-work]

@thegecko One little thing before merging, if possible: it would be nice to squash the 3 commits into a single one.