Checkmk Werk 13151: Don't crash if SLAs are displayed in views

ID: 13151 Title: Don't crash if SLAs are displayed in views Component: Multisite Level: 1 Class: Bug fix Version: 2.1.0i1 If an SLA was used in a view the site crashed and showed the error message "Internal error: a bytes-like object is required, not 'str'". This is fixed. This commit also fixes some small styling issues for SLAs.