Fix leading zero problem in YAML front matter

[joeyaiello]

Apparently you need to put single quotes around numbers with leading zeros in YAML, and many of our RFC numbers are probably wrong because of this. We should fix it.

[JamesWTruher]

Filename

RFC0003-Lexical-Strict-Mode.md RFC0001-Mutual-Exclusion-Parameters-and-Properties.md RFC0053-PowerShell-IoT-Module.md RFC0005-Typed-Interprocess-communication.md RFC0006-Universal-Parsing-and-Piping.md RFC0007-Weak-Aliases.md RFC0009-Glob-for-Native-Tools.md RFC0011-Dot-Referencing-With-Static-Integers.md RFC0002-Generalized-Splatting.md RFC0018-Get-StringHash.md RFC0004-PowerShell-Module-Versioning.md RFC0049-PSModulePath.md RFC0050-Importing-Windows-PowerShell-modules-in-PowerShell-Core.md RFC0051-Null-conditional-operators.md RFC0052-Notification-On-Version-Update.md