This is required for `set -u` to work since this variable isn't required
to be set.

This adds `set -u` to both the frameworks and resources copy shell
scripts. This means that if the scripts attempt to reference any
variable that is undefined, they will fail.

[Sandbox] Clean up usage of #local?

Only add resources and frameworks build phase when needed

A recent version of git has changed what whitespace it outputs

This changes the project integrator to only add build phases to the
user's project if there are resources of frameworks that will be copied
in that phase.

Clear input/output paths if they exceed an arbitrary limit

Warn instead of throwing an exception when dev pod's license file is missing

Warn instead of throwing an exception when a development pod's podspec specifies a license file that does not exist

Better static frameworks transitive dependency error checking

Store spec repos in the Lockfile

Always update input/output paths even if they are empty

 [Examples] Get examples building with Xcode 9

[Repo::Push] Allow disabling overwriting published specs

Unique all available pre-release versions when displaying

Do not attempt compilation for pods with no sources and skipping import validation

Set direct and transitive dependency header search paths for pod targets

Log target names missing host for libraries

Previously we only logged the target name if the target missing a host
wasn't a framework target. Logging it for framework targets as well can
be useful for debugging Podfile configuration issues.

Release 1.4.0

# gpg: Signature made Thu Jan 18 14:56:04 2018 PST
# gpg:                using RSA key 01195BB315DDA856
# gpg: Good signature from "Samuel Giddins <segiddins@segiddins.me>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 7B19 37A9 CF66 AEF6 52C9  4090 0119 5BB3 15DD A856