Add configurable store timeout

[snailxr]

No description provided.

[snailxr]

@sgotti Can you review the pull request?

[sgotti]

@snailxr Thanks for the PR. It LGTM. Please rebase and squash in a single commit adding a better commit message, something like:

*: Add configurable store timeout

Add a command line option to set the store timeout.

[sgotti]

@snailxr integration tests are failing since the new Store.Config Timeout field introduced in this patch is not set (and will default to 0) when creating the tests stores in https://github.com/sorintlab/stolon/blob/master/tests/integration/utils.go

[snailxr]

@sgotti Is there a easy way to run the integration tests locally? 😃

[sgotti]

@snailxr

• Use a local agola and execute a direct run (also change the .agola/config.jsonnet to remove unneeded tasks)

• test a specific store with INTEGRATION=1 STOLON_TEST_STORE_BACKEND=etcdv3 PARALLEL=5 bash -x ./test. It requires an etcd v3.x binary in your PATH. It'll use your local installed version of postgres.

[sgotti]

@snailxr Integration tests are now successful.

Since a new command line option as been added, also the doc should be regenerated.

You should execute ./scripts/gen_commands_doc.sh and commit changes to the doc/commands files.

[snailxr]

@sgotti The command documents regenerated

[sgotti]

@snailxr Thanks! Merging.