Increase default timeout of Context when making OCI calls.

[jlamillan]

Greetings!

This pull-request resolves #387 by increasing the default timeout of HTTP requests to OCI from 10 seconds to 5 minutes.

5 minutes may seem excessive, but (1) the compute.GetInstanceByNodeName() function needs time to iterate through potentially all the VNICs in a compartment and (2) we have a customer running a cluster of hundreds of nodes (and several hundred VNIC attachments) and we have confirmed that it requires several minutes to complete.

[coveralls]

Pull Request Test Coverage Report for Build 2399182508

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 29.32%

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Totals
Change from base Build 2369846621:	0.0%
Covered Lines:	2581
Relevant Lines:	8803

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💛 - Coveralls