Address all Rubocop TODOs

[abotalov]

Rubocop was introduced in #43.
We should address TODOs one by one - create a PR per one / several offenses to ease reviewing.

• Layout/AlignArguments
• Layout/EmptyLineAfterGuardClause
• Layout/ExtraSpacing
• Layout/LeadingCommentSpace
• Layout/MultilineOperationIndentation
• Layout/SpaceAfterComma
• Layout/SpaceAroundEqualsInParameterDefault
• Layout/SpaceAroundOperators
• Layout/SpaceInsideBlockBraces
• Layout/SpaceInsideHashLiteralBraces
• Layout/TrailingWhitespace
• Lint/ParenthesesAsGroupedExpression
• Lint/UnneededRequireStatement
• Lint/UriEscapeUnescape
• Metrics/AbcSize
• Metrics/BlockLength
• Metrics/ClassLength
• Metrics/CyclomaticComplexity
• Metrics/MethodLength
• Metrics/ModuleLength
• Metrics/PerceivedComplexity
• Naming/UncommunicativeMethodParamName
• Security/YAMLLoad
• Style/BracesAroundHashParameters
• Style/CommentedKeyword
• Style/ConditionalAssignment
• Style/Documentation
• Style/EmptyElse
• Style/ExpandPathArguments
• Style/FormatString
• Style/FormatStringToken
• Style/FrozenStringLiteralComment
• Style/GlobalVars
• Style/GuardClause
• Style/HashSyntax
• Style/IfUnlessModifier
• Style/ModuleFunction
• Style/MutableConstant
• Style/NumericPredicate
• Style/PercentLiteralDelimiters
• Style/RescueStandardError
• Style/SafeNavigation
• Style/SignalException
• Style/SpecialGlobalVars
• Style/StringLiterals
• Style/SymbolArray
• Style/TernaryParentheses
• Style/TrailingCommaInHashLiteral
• Metrics/LineLength