Use editor.tabLength config value when creating edit sessions

Closes #708

spec/project-spec.coffee

@@ -66,6 +66,11 @@ describe "Project", ->
       Project.unregisterOpener(barOpener)
 
     describe "when passed a path that doesn't match a custom opener", ->
+      it "creates the edit session with the configured `editor.tabLength` setting", ->
+        config.set('editor.tabLength', 4)
+        editSession = project.open('a')
+        expect(editSession.getTabLength()).toBe 4
+
       describe "when given an absolute path that hasn't been opened previously", ->
         it "returns a new edit session for the given path and emits 'buffer-created' and 'edit-session-created' events", ->
           editSession = project.open(absolutePath)

src/editor.coffee

@@ -23,6 +23,7 @@ class Editor extends View
     normalizeIndentOnPaste: true
     nonWordCharacters: "./\\()\"':,.;<>~!@#$%^&*|+=[]{}`~?-"
     preferredLineLength: 80
+    tabLength: 2
 
   @nextEditorId: 1
 

src/project.coffee

@@ -39,7 +39,6 @@ class Project
     repoName = repoName.replace(/\.git$/, '')
     path.join(config.get('core.projectHome'), repoName)
 
-  tabLength: 2
   softTabs: true
   softWrap: false
   rootDirectory: null
@@ -372,7 +371,7 @@ class Project
     editSession
 
   defaultEditSessionOptions: ->
-    tabLength: @tabLength
+    tabLength: config.get('editor.tabLength')
     softTabs: @getSoftTabs()
     softWrap: @getSoftWrap()