Clean up embertemplatelint code

Alias ember-template-lint to embertemplatelint so users can use either
string to enable the linter.

test/command_callback/test_embertemplatelint_command_callbacks.vader

@@ -0,0 +1,17 @@
+Before:
+  call ale#assert#SetUpLinterTest('handlebars', 'embertemplatelint')
+
+  GivenCommandOutput ['1.6.0']
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(ember-template-lint executables runs the right command):
+  AssertLinter 'ember-template-lint',
+  \ ale#Escape('ember-template-lint') . ' --json --filename %s'
+
+Execute(old ember-template-lint executables runs the right command):
+  GivenCommandOutput []
+
+  AssertLinter 'ember-template-lint',
+  \ ale#Escape('ember-template-lint') . ' --json %t'

test/test_embertemplatelint_executable_detection.vader

@@ -1,22 +0,0 @@
-Before:
-  call ale#test#SetDirectory('/testplugin/test')
-
-  runtime ale_linters/handlebars/embertemplatelint.vim
-
-After:
-  call ale#test#RestoreDirectory()
-  call ale#linter#Reset()
-
-Execute(ember-template-lint executables runs the right command):
-  call ale#test#SetFilename('ember-template-lint-test-files/app/template.hbs')
-
-  AssertEqual
-  \ ale_linters#handlebars#embertemplatelint#GetCommand(bufnr(''), [2, 0, 0]),
-  \ '%e --json --filename %s'
-
-Execute(old ember-template-lint executables runs the right command):
-  call ale#test#SetFilename('ember-template-lint-test-files/app/template.hbs')
-
-  AssertEqual
-  \ ale_linters#handlebars#embertemplatelint#GetCommand(bufnr(''), [1, 5, 0]),
-  \ '%e --json %t'