Update @ember/test-helpers to v0.7.26.

[rwjblue]

Release notes

• #410 Use assign instead of deprecated merge. (@wagenet)

• #397 Add typeIn helper to trigger keyup, keypress and keyup events when filling inputs. (@mfeckie)

• #398 Add options to click, doubleClick, and tap. (@BryanCrotaz)

• #387 Update buildMouseEvent to use MouseEvent constructor if it is present. (@ggayowsky)

• #391 Add numbers to keyFromKeyCode. (@localpcguy)

• #392 Include selector in waitFor()'s default timeout message. (@gabrielgrant)

• #382 Add doubleClick helper. (@mmun)

• #413 Clear requests array when tearing down. (@hjdivad)

• #404 Fix getRootElement failing when Application.rootElement is an element. (@apellerano-pw)

• #408 Update setupApplicationContext documentation. (@vitch)

• #340 Add some specific documentation for uploading files. (@jrjohnson)

• #396 docs(api): try fixing getSettledState list. (@knownasilya)

• #199 Replace hard-coded guides link with /current. (@acorncom)

• #386 Fix waitFor return value documentation. (@pcambra)

• #412 Work around downstream dependencies dropping Node 4 without major bump. (@rwjblue)

• Andrew Pellerano (apellerano-pw)
• Bryan (BryanCrotaz)
• David Baker (acorncom)
• David J. Hamilton (hjdivad)
• Gabriel Grant (gabrielgrant)
• Ilya Radchenko (knownasilya)
• Jonathan Johnson (jrjohnson)
• Kelvin Luck (vitch)
• Martin Feckie (mfeckie)
• Martin Muñoz (mmun)
• Mike Behnke (localpcguy)
• Pedro (pcambra)
• Peter Wagenet (wagenet)
• Robert Jackson (rwjblue)
• ggayowsky