fix(docs) Clear description of update server changes TBD

Pulling in @philips' changes from coreos/coreos-cloudinit#6 after
trashing PR coreos/coreos-cloudinit#20.  Cleanup of that PR was
beyond my git-fu.

cc @jonboulle
fix(doc) more sensible ordering

It makes a bit more sense to specify the scope of the section
before getting into details about how it's done.
removed tricky space from cloud-config header
Trim newlines from the cloud-config-url kernel parameter and added a test

- In the Fetch function trim whitespace from /proc/cmdline
- New test for Fetch function
- Added Location field to the procCmdline struct for testing
Merge pull request #121 from iamveen/master

removed tricky space from cloud-config header
Merge pull request #120 from brianredbeard/pr20-fix

fix(docs) Clear description of update server changes
Merge pull request #111 from namsral/patch-1

Trim newlines from the cloud-config-url option
feat(util/http_client): Adds generic HTTP client

Supports retries with exponential backoff as well as connection
timeouts and the ability to skip SSL/TLS verification.

This commit also refactors datasource and initialize packages
in order to use the new HTTP client.
style(util->httpbackoff): Changes package as per @philips suggestion
style(httpbackoff -> pkg): Adjusts package name to follow convention
fix(pkg/http_client): Printf is smarter than you think

Printf determines what the duration unit is
and prints it accordingly.
Merge pull request #123 from c4milo/shared-http-client

feat(util/http_client): Adds generic HTTP client
fix(update): locksmith service does not need disabling/enabling
Merge pull request #125 from jonboulle/no_locksmith_enable

Dies trying to enable non-existent /etc/systemd/system/locksmithd.service
fix(systemd): EnableUnitFile unit name rather than absolute destination
Merge pull request #127 from jonboulle/127

"Enable" option does not support units in /usr/lib64/systemd
chore(coreos-cloudinit): bump to 0.7.2
chore(coreos-cloudinit): bump to 0.7.2+git
fix(pkg): simplify exponential backoff to avoid overflows
fix(systemd): remove any existing unit when calling mask