Introducing Pillar Framework

Refactor of pillar-server and pillar-web into a single python package. This
simplifies the overall architecture of pillar applications.

Special thanks @sybren and @venomgfx

src/styles/_error.sass

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+body.error
+	width: 100%
+	height: 100%
+
+#error_container
+	display: flex
+	justify-content: center
+	align-items: center
+	position: absolute
+	top: 0
+	left: 0
+	right: 0
+	bottom: 0
+	background-color: darken($color-background-nav, 3%)
+
+	&.standalone
+		width: 100%
+		height: 100%
+		position: fixed
+
+		#error_box
+			.error-lead
+				padding: 10px 10px
+
+				p
+					display: block
+
+				&.extra
+					padding-top: 0
+
+
+	#error_box
+		min-width: 60%
+		max-width: 500px
+		text-align: center
+		display: flex
+		justify-content: center
+		align-items: center
+		flex-direction: column
+
+		+container-box
+
+		box-shadow: 0 0 15px rgba(black, .2)
+		padding: 0
+		background-color: $color-background-nav
+
+		.error-top-container
+			position: relative
+			width: 100%
+			background-color: $color-background-nav
+			background: repeating-linear-gradient(-45deg, lighten($color-background-nav, 2%), lighten($color-background-nav, 2%) 10px, $color-background-nav 10px, $color-background-nav 20px)
+
+		.error-title
+			padding: 25px 0 10px 0
+			color: white
+			font:
+				family: $font-headings
+				size: 2em
+				weight: 300
+
+		.error-lead
+			width: 100%
+			padding: 0 25px 25px 0
+			line-height: 1.6em
+
+			color: $color-text-light-primary
+			font:
+				family: $font-body
+				weight: 300
+
+			a
+				text-decoration: none
+				&:hover
+					text-decoration: underline
+
+			&.extra
+				padding: 25px 0
+				font-size: .9em
+				color: $color-text-light-secondary
+
+
+		hr
+			margin: 0 0
+			width: 100%
+			border: none
+			height: 3px
+			background-color: lighten($color-background-nav, 5%)
+
+		.buttons
+			margin: 0 15px 25px 0
+
+			a
+				font-size: 1.2em
+				margin: 0 15px
+				&.sign-up
+					@include button-rounded-filled($color-primary, 999em)
+				&.sign-in
+					@include button-rounded($color-background, 999em)
+					border-color: transparent
+
+
+#node-overlay
+	#error_container
+		@include overlay(rgba($color-background-nav, .8), 0%, transparent, 60%)
+
+		#error_box
+			top: 50px
+			position: absolute
+			left: 50%
+			transform: translateX(-50%)
+			border-radius: 3px
+			box-shadow: 0 0 100px rgba(black, .85)
+			overflow: hidden