Fix issue 6269:  IMAP LOGIN failure
Fix issue 6269:  IMAP LOGIN failure

Some IMAP servers are broken and don't correctly handle string
literals with the LOGIN command.

This switches to using quoted strings instead.

This is what Thunderbird does.

jberkel/k-9,KitAway/k-9,philipwhiuk/q-mail,vasyl-khomko/k-9,denim2x/k-9,cliniome/pki,gnebsy/k-9,dhootha/k-9,WenduanMou1/k-9,msdgwzhy6/k-9,msdgwzhy6/k-9,icedman21/k-9,leixinstar/k-9,herpiko/k-9,Eagles2F/k-9,crr0004/k-9,crr0004/k-9,jca02266/k-9,github201407/k-9,rishabhbitsg/k-9,gilbertw1/k-9,tsunli/k-9,deepworks/k-9,philipwhiuk/q-mail,KitAway/k-9,Eagles2F/k-9,sanderbaas/k-9,github201407/k-9,mawiegand/k-9,ndew623/k-9,vatsalsura/k-9,sebkur/k-9,dgger/k-9,k9mail/k-9,rollbrettler/k-9,XiveZ/k-9,deepworks/k-9,vt0r/k-9,GuillaumeSmaha/k-9,thuanpq/k-9,bashrc/k-9,dpereira411/k-9,cketti/k-9,cketti/k-9,439teamwork/k-9,vasyl-khomko/k-9,dhootha/k-9,suzp1984/k-9,deepworks/k-9,thuanpq/k-9,rishabhbitsg/k-9,cliniome/pki,rollbrettler/k-9,gaionim/k-9,dgger/k-9,gnebsy/k-9,bashrc/k-9,dpereira411/k-9,roscrazy/k-9,GuillaumeSmaha/k-9,sonork/k-9,dpereira411/k-9,torte71/k-9,vasyl-khomko/k-9,huhu/k-9,torte71/k-9,cketti/k-9,suzp1984/k-9,gaionim/k-9,k9mail/k-9,crr0004/k-9,k9mail/k-9,ndew623/k-9,philipwhiuk/k-9,vatsalsura/k-9,indus1/k-9,herpiko/k-9,herpiko/k-9,tonytamsf/k-9,cooperpellaton/k-9,icedman21/k-9,G00fY2/k-9_material_design,farmboy0/k-9,thuanpq/k-9,439teamwork/k-9,moparisthebest/k-9,sonork/k-9,indus1/k-9,bashrc/k-9,konfer/k-9,jberkel/k-9,nilsbraden/k-9,mawiegand/k-9,moparisthebest/k-9,sedrubal/k-9,nilsbraden/k-9,sanderbaas/k-9,gaionim/k-9,dgger/k-9,WenduanMou1/k-9,konfer/k-9,tsunli/k-9,sonork/k-9,huhu/k-9,Valodim/k-9,sanderbaas/k-9,roscrazy/k-9,torte71/k-9,KitAway/k-9,denim2x/k-9,G00fY2/k-9_material_design,philipwhiuk/k-9,leixinstar/k-9,gilbertw1/k-9,moparisthebest/k-9,tsunli/k-9,tonytamsf/k-9,jca02266/k-9,leixinstar/k-9,ndew623/k-9,XiveZ/k-9,cketti/k-9,suzp1984/k-9,sebkur/k-9,philipwhiuk/q-mail,sebkur/k-9,sedrubal/k-9,cliniome/pki,mawiegand/k-9,farmboy0/k-9,konfer/k-9,msdgwzhy6/k-9,gnebsy/k-9,cooperpellaton/k-9,icedman21/k-9,WenduanMou1/k-9,CodingRmy/k-9,tonytamsf/k-9,XiveZ/k-9,farmboy0/k-9,cooperpellaton/k-9,jca02266/k-9,rollbrettler/k-9,nilsbraden/k-9,Eagles2F/k-9,github201407/k-9,CodingRmy/k-9,huhu/k-9,vt0r/k-9,GuillaumeSmaha/k-9,denim2x/k-9,gilbertw1/k-9,dhootha/k-9,439teamwork/k-9