Remove rubocop and msftidy touchpoints

This replicates PR rapid7#3639 for the staging/electro-release branch

Rubocop replaces the default YAML library which makes development
testing difficult. It does not cause problems on Travis, but according
to reports, it does cause instability with many individual dev
environments.

While I would love to have a more solid source of this bug report, right
now this was an oral report from @shuckins-r7 (who I tend to believe a
lot).

(Conflict resolved on rubocop.yml)

.rubocop.yml

@@ -1,19 +0,0 @@
-LineLength:
-  Enabled: true
-  Max: 180
-
-MethodLength:
-  Enabled: true
-  Max: 100
-
-Style/ClassLength:
-  Exclude:
-    # Most modules are quite large and all contained in one class.  This is OK.
-    - 'modules/**/*'
-
-Style/NumericLiterals:
-  Enabled: false
-
-Documentation:
-  Exclude:
-    - 'modules/**/*'

Gemfile

@@ -15,8 +15,6 @@ group :db do
 end
 
 group :development do
-  # Style/sanity checking Ruby code
-  gem 'rubocop'
   # Markdown formatting for yard
   gem 'redcarpet'
   # generating documentation

tools/msftidy.rb

@@ -335,15 +335,6 @@ class Msftidy
     end
   end
 
-  # Explicitly skip this check if we're suppressing info messages
-  # anyway, since it takes a fair amount of time per module to perform.
-  def check_rubocop
-    return true if SUPPRESS_INFO_MESSAGES
-    out = %x{rubocop -n #{@full_filepath}}
-    ret = $?
-    info("Fails to pass Rubocop Ruby style guidelines (run 'rubocop #{@full_filepath}' to see violations)") unless ret.exitstatus == 0
-  end
-
   def check_old_rubies
     return true unless CHECK_OLD_RUBIES
     return true unless Object.const_defined? :RVM
@@ -611,7 +602,6 @@ def run_checks(full_filepath)
   tidy.check_vuln_codes
   tidy.check_vars_get
   tidy.check_newline_eof
-  tidy.check_rubocop
   tidy.check_sock_get
   tidy.check_udp_sock_get
   return tidy