Mention asking questions in the README

Asking questions using Issues isn't all that common, this adds a sentence to the `README` assuring people that it's fine and encouraged.
Merge pull request #1082 from ReactiveCocoa/ask-us-questions

Mention asking questions in the README
Updated xcconfigs submodule to fix clang error on Xcode 5.1 due to deprecated linker flag (Fixes #1050)
Guard signal names with RAC_DEBUG_SIGNAL_NAMES.
Merge pull request #1084 from JaviSoto/feature-xcode51-clang-error

Updated xcconfigs submodule to fix clang error on Xcode 5.1 due to deprecated linker flag
Update the doc.
Merge pull request #1086 from ReactiveCocoa/debug-signal-names

Guard signal names with RAC_DEBUG_SIGNAL_NAMES.
Non-collaborators can't apply labels to issues

/cc @dannygreg
Added more info links.
Merge pull request #1095 from AshFurrow/ashfurrow-links

Added more info links.
-rac_textSignal should accommodate IB 'clear when editing begins'
Updated comments & channel events for the previous change
Added test case for -rac_textSignal, adjusted formatting
Remove old demo app links

Resolves #1100.
Merge pull request #1103 from ReactiveCocoa/jspahrsummers-patch-1

Remove old demo app links
Cleaned up rac_textSignal clearsOnBeginEditing test
Merge pull request #1098 from drhr/master

rac_textSignal should accommodate 'clear when editing begins'
Change RAC_DEBUG_SIGNAL_NAMES into an envvar
Vary -rac_description behavior based on the envvar too
Use sel_getName in signal naming to avoid allocations

Selector names are cheaper to retrieve as C strings than to wrap in
NSStrings.