ChangeEditUtil: Provide CurrentUser instead of IdentifiedUser

The implementation of Provider<IdentifiedUser> in
ThreadLocalRequestContext throws a ProvisionException in get() before
we can call isIdentifiedUser() on it. This fix should throw the proper
exception when the user is not signed in.

Change-Id: I404564652176897a24c4570734475c5b9f5c2bca
EmailReviewComments: Throw OutOfScopeException for current user

This matches the behavior of ChangeMergeQueue's RequestContext
implementation, and replaces a lurking NPE with a more descriptive
error.

Change-Id: I35dfd750980df70173a797b5b2147ee88d715b77
fix documentation of REST API change query field.

The reference to PATCHSET_LINKS is incorrect, it should be WEB_LINKS.

Change-Id: I8c8f87bd31b5a89760393dc73e099e9acdcb8b12
ChangeApiImpl: It is useless to use provider on singletons

Change-Id: Ic262faf10be101c7b960fc3a7ec73b7eab8a5c84
Fix button styles on CS2 and project screen

Id5d62b830 was trying to fix wrong ActionButton style on project info
screen, but broke the style on CS2 instead. Fix it in both places.

Test Plan:

Deploy cookbook-plugin and verify the style of "Say hello" button.
Verify the style of "Create change" button on project info screen.

Bug: issue 2906
Change-Id: Ia2a46e83ebe780c6b3304a8aba97aa7876dba2fa
Merge "ChangeApiImpl: It is useless to use provider on singletons"
Fix typo in dev documentation

Change-Id: Iec758ba00da6c4c2b5d8bd3b2816ad87b6c32022
Merge "Fix typo in dev documentation"
Merge "fix documentation of REST API change query field."
Buck: Document how to disable buckd

See this bug report for references [1].

[1] https://github.com/facebook/buck/issues/197

Reported-by: David Borowitz <dborowitz@google.com>
Change-Id: I2113251a1be5597810b9680b64d09e18df8588dc