Update main project to use Gridicons 1.0-beta.1 pod

[mindgraffiti]

Issue

I went to merge wordpress-mobile/WordPressAuthenticator-iOS#207 and #2007. Unfortunately, the Authenticator recently had a Gridicons pod update to 1.0-beta.1. Since the Gridicon pods can't be out of sync for version numbers in Authenticator podfile and in the main project's podfile, this PR must be approved before I can merge in #2007.

In this PR

• updates the Authenticator to point to the latest pod changes, which upgraded Gridicons from 0.20 -> 1.0
• updates the main podfile to Gridicons 1.0
• find / replace deprecated Gridicons method calls

To Test

1. rake dependencies
2. Build and run
3. Choose an icon at random from the code to smoke-test

Update release notes:

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[jaclync]

Code: ✅
Testing: ✅

example screenshots:

order details	order notes

[mindgraffiti]

Thanks @jaclync !